https://thepointsguy.com/news/jetblu...-changes-2022/
I think this article's interview with Don Uselmann shows that this is just the first part of the changes to mosaic program. There will be more benefits/enhancements coming.
Given how bad JetBlue IT is, the biggest challenge to changing mosaic program was how to add a new tier, how to have an upgrade system for mint and how to achieve free EMS upgrades. Admittedly, the last one probably didn't require much work. The first two probably required quite a bit of changes. It was most likely done to align themselves with AA. Now, mosaic is essentially somewhere around Platinum and mosaic+ is a little bit harder than EXP. Even the number of upgrades is the same as you would get when you initially hit EXP status.
They didn't put that much IT resources into these things for the new tier and benefits to go away after one year. Most likely, we going to see some more reciprocal benefits with AA. Maybe they can align themselves with AS also. We might get a 3rd tier (like AA gold) in 2023. The upgrade process will probably get refined. Maybe the founder membership goes away and some other benefits come in.