I don't love the demoman changes exactly, but I don't see it as the end of the world. I do hope they tweak it a touch along the lines of Ma3laa's suggestion, but it isn't killing the game.
Zoltan I've played on a team multiple times with a friend who plays demoknight with a controller, and he played it on my 6s team. You could still do effective rollouts with it and the loose cannon, you had decent area denial with it, and if you could reliably airbust with it, scouts could be fought.
http://www.ugcleague.com/team_page.cfm?clan_id=9010
http://www.sizzlingstats.com/stats/144531
I ain't sayin' but I'm just sayin'.