1989 is a long time between drinks! Still, my money is on Mustaine being the most likely of the two to produce an album that somewhat resembles thrash this year...
well from what i heard of their last one, it was a step in the right direction and it held alot of potential. If they weed out some of the slower, melodic tunes and write some more faster stuff then Megadeth would be well on the way to thrashville IMO. I wouldnt expect a masterpiece like Peace Sells, they will never record raw and ripping thrash like the early years but some decent thrash tunes is not completely out of the question.