As Eric Rosen explained to me a couple weeks ago, Alexander Shabalov revived 7...b5!? against Sam Shankland in this year's U.S. Championship. Shabalov's primary contribution seems to be the realization that after 8.a4, the critical move is 8...b4!
Dmitry is Eric's teacher, so I suspect the two of them have been working on this line together. The engines tell me that in yesterday's game against six-time Dutch champion Loek Van Wely, Gurevich was better after 14 moves and simply winning after 16...Bf6! Dmitry finished the game in style with a bishop sac and a rook sac. Impressive preparation and play against a super GM!