Still I expected them to try harder this time, because the technologies to develop a good GPU, are strategically important in other areas too
I think I read somewhere that they're having problems getting AIB partners for Battlemage. That would be a significant impediment for continuing in the consumer desktop market unless Battlemage can perform better (business-wise) than Alchemist.
They probably will continue investing in GPU even if they give up on Arc, it might just be for the specialized stuff.
Disowning current tariffs doesn't mean they'll go away, either, though.
Tariffs are easy to put in place, but hard to roll back. You can put then in place on a whim, basically, but then the target country will retaliate with their own. As a result, removing them requires diplomatic negotiation to make sure the removal is bilateral. That's not easy to do during times of icy relations like China and we currently have.