The original members of Alpha Flight weren't killed by the Collective. During the third run of Alpha Flight the original team during an adventure on the Plodex homeworld remained behind while the newer members of the team returned to earth. At the end of the series, during a time travel storyline, the new team brought membersof the old team forward through time from the momewnt of Guardians original supposed death.
It is this team from an alternate past that was killed by the Collective. The original team of Guardian etc are all still on the Plodex homeworld.
So bringing back Alpha Flight is quite easy. The problem is getting a creative team that can do them justice and create stories wqe want to read.
A bigger problem is that really theyre all still rather boring and even if the original cast can be brought back I'm not sure that the comic reading public at large will really give a damn in a world dominated by a dozen Avengers and X-Men titles with frankly more dynamic rosters.