I don't think any client will have total control. I'm wondering, is it theoretically possible to go back to how it was before, i.e. pre-taproot where large amounts of data couldn't be stored in a tx? Maybe I'm not making sense because I don't understand all the ways data can be included.
Discussion
Yes it’s possible but would require a fork.
You can get creative and find any which way to include 'data'; the only things where you couldnt is with a hash or pubkeys you actually have the private key for. Well you could...but that would require bruteforcing...proof of work if you will ;)