why's that?

No. Liquid glass wont even make it past 1 macOS/iOS release. In fact Apple has already scaled back many of the glass UI parts they've shown in the earlier demos and betas.

It's an ill-though change for change's sake. Nobody is that impressed.

Flat design was more fully thought. But even that was useless and ultimately user hostile.

"Skeuomorphic" (which is mistankenly called that, few parts of OS X or Windows at the time were actually skeuomorphic in nature) was just better UI.

no

edit: and I hope not.