The US is planning for a new tank roundabout 2030. While right now it notionally is going to be an Abrams derivative, it is almost certainly going to be a completely overhauled new design and not a retrofit of existing tanks like what has been happening to Abrams.
Just something to point out to people who complain about the U.S. gifting stocks of vehicles to Ukraine. The U.S. was planning to get rid of them anyway.
The F-35 is an expensive program, and has undeniably had cost overruns, but from some of the poking around it seems the issues have also been exaggerated or different issues have been conflated, so without doing a deep dive, it is hard to say if the program is worth the bang or not.