Is this mamedev's answer ? I mean do you guys plan to leave it as it is (poor and bad options for sync and lag) and just tell people to buy G/Free-Sync compatible hardware ?
If so then it really looks like GroovyMAME was in fact assimilated to make murdering it easier/smoother, or politically acceptable, and the superior solutions it offered in that field will never come back whether as GM or whithin baseline, or if they do it'll be God knows when maybe in a decade.