Just been speaking to TPLink support and they are now confirming that there are no plans to increase the number of enabled Smart Actions from 3. This is despite their FAQs stating there is a "selective group" getiing full access and that there is a "waiting list":-
"Q3: How many Smart Actions can be enabled at a time?
A: Up to 3 Smart Actions can be enabled at the same time.
Q4: Why it says “coming soon” in the Smart Actions tab?
A: Smart Actions is rolling out stage-by-stage to Kasa users. A selective group of Kasa users will be supported first where they have the full access to the Smart Actions, while other users are in the waiting list."
This is just not acceptable when you're spent a good deal of money buying extra cameras and plugs, and now a monthly subscription to keep the functionality you previously had free(!), on the basis that TPLink has said full access is being rolled out.