Sure, ECC could make a software change that eliminates t-addresses. So could anybody! So could the Zcash Foundation. So could anyone else with even a little bit of software development skill. In fact, anyone who wants to do that could probably just use that software change that one of the Zcash-clones has done. I think it’s called “ARR Chain”? There are one or more Zcash clones out there that have already made this software change.
What ECC can’t do — and what literally nobody on this planet can do — is force people to download and run that software and put their money into it.