this is great news!  (I'll believe it when I see it).  I think the neutral wire provides the power for the switches...but could be wrong.

@funkhouse9

A smart switch without a neutral is very unlikely (maybe impossible). For a few reasons:
#1 US National Electric code changed in 2011 to _require_ a netral in every swtich box (including for remodels). I'm fairly certian most modern electrical codes in other countries similarly require a neutral wire be provided in every box. Yes there are still a lot of old switch boxes without a neutral, but most existing 3-way switch boxes probably do have a neutral.

#2 Any swtich with solid state internals (ie all smart swtiches) needs constant power to power them (wifi, indicator lights, etc) so you pretty much have to have hot+netrual to them at all times even when the light being controled is off*.

Sorry to rain on your parade...  

TopGreener makes a 3-way dimmer (I just put them in), it uses some very peculiar wiring where one traveler is always hot but with a variable volatage for dimmer, it works, but I'm a little surprised it meets code...  So, who knows maybe there is a way just I find it highly unlikely.

@Carl this is great news. I wish I'd know a day sooner an I wouldn't have wasted $100 on those topgreener swtiches, but I'm still happy to hear it's planned.  Those 3-way dimmer swtiches do let me control dimming from either end, and via their app, but...  fatal flaw for me is that while their app does scheduling, it is only simple on/off, one can't schedule a specific brightness setting like one can with tp-link's exclent app. Wtih TopGreener I can set brightness via the app manually, just not via a schedule. Anyway, please do pass on to engineering that setting brightness via scheduled actions on the future 3-way swtich is super important!

Also maybe tell them that while I'll settle for "whatever works" the wiring for TopGreener's switches was freaking bizzare (using varible voltage on the traveller). I'd love it if TP-Link found a better way, like having the two switches communicate dimming state wirelessly... which seem obvious.

@jb510 You're not raining on my parade. Lutron Caseta makes a no-neutral dimmer switch that's controlled by remote which is not a literal 3-way switch, but it meets the need. C by GE is promoting no-neutral options for release this year on their site which were promoted fairly heavily following CES. From the GE website: "Hubless 3-Wire Smart Switches An industry first, these award-winning smart switches and dimmers work in almost every home, including older homes without neutral wires. No hub is required to enable voice control and out-of-home control for your smart and traditional light bulbs. They work with most residential wiring and feature a slim design for easy installation. Available in dimming + motion sensing, dimming, and on/off varieties." The options are clearly starting to creep into the market. I was simply making the point that thinking ahead instead of just catching up is a good business practice. I like TP Link which is why I'm here giving sincere feedback. But the reality is consumers like me do need (want) no neutral options and are itching to expand their smart home setups.

@Carl 

I was so happy to read that the 3-way dimmer will be coming out this year!! I need many of these and did not want to change from Kasa/TP-Link. Thank you, thank you! Can't wait until they are released. 

@funkhouse9 are you kidding me... They are making the 3 way dimmer based off our request and your already complaining.. 

@Astone595 Who is complaining? I made a legitimate product suggestion and when another user noted it wasn't possible, I provided supporting information showing that other companies are doing it and simply suggested that they could (and perhaps should) take this opportunity to aim in that direction when designing this. I haven't complained once, so thanks for giving me a hard time.

@funkhouse9 This is just one of the 3 way dimmer switch threads...there are others, dating back years.   Lets all hope that they actually produce one this year!  And a 4 way!

@KleyP I suggested a no-neutral option and got scolded. I trust they'll also scold you for suggesting a 4-way option since we're both being ungrateful now that they're actually talking about making a 3-way version. (Just to be clear, I'm trying to be funny.)  I'd love to know how many people who have posted in this thread don't actually realize that the white wire they may or may not have at their switch isn't actually a neutral. I seriously doubt this thread is full of electricians with recently built homes. 

@funkhouse9 your reply was spot on and certainly not complaining.  Ignore the trolls just ranting and looking for drama. 
 

i wouldn't call lutrons setup a switch, I'd call it a battery operated remote since it has no wires at all.  Lol.  It is a awesome and unique solution to this though and it would be cool if tplink offered a wireless remote like that as well.  
 

there are a couple issues with tplink copying Lutron Casettas wireless remote though:

it's battery powered.  
lt communicates with a smart hub (zwave, zigbee, I forget which), not WiFi.  
 

Making a battery powered WiFi switch is impractacle/impossible due to power consumption of an always on radio, but tplink could build a little repeater/hub that plugged into the wall and recover signals from a battery powered switch.

Again, though that seems unlikely given how much gear would need to be designed and sold just to support this one use when everything else the make is WiFi only (which is why I use it).

The casetta system is really great though. IMHO the best hardware out there if you don't mind needing a hub or having to run a separate system for smart plugs (which honestly was the biggest factor for me). 
 

@Carl 

Thanks for sharing the information about the upcoming 3-way dimmer.  This is great news.  

One of my messages had a request that dimmers could be grouped together using Smart Actions.  I have that set up today to allow on-off functions of two different HS220s to control each other, but Smart Actions don't allow triggers/changes based on the dimming setting.  This might be something that could be done in software without needing a new product.  Is this something that has been communicated to the product team?