Joseph,
Great question, any time a new feature such as this comes out questions of updates always follow. Customers want to be up to date and also have the most protection so that is understandable. When it comes to implemetation it is actually less to do with the manufacture or the provider in this Case TP-Link and Google and more to do with the maker of the chipset the product uses. Like with network adapters and compatiblity with new OS versions, features can only be added if the chipset is compatible. If compatible and the chipset maker adds the feature we are then able to make firmware or drivers add the feature or compatibliy. As of right now we have not recieved word form chipset makers on any existing product if support for WPA3 will be added.
For the Onhub we are acutally only OEM so we don't keep much information on that product on our website. The best source to keep updated on if and when the WPA3 feature might be added is Google Onhub support team.
Best Regards
Carl | TP-Link Support