You still won't be able to pick your time. The change is basically you now don't have to cancel your existing LL to pick a different one.
I have my doubts. My thoughts are it will eventually end up similar to Express Pass without the resort benefit. I say that cause there isn't enough capacity for
Genie+, FP+ or FP to work for everyone to have access to it. It's a big reason all other parks limit availability for their Skip the line passes.