I believe Bioware mentioned that the comic follows Biowares canon, so if you made Alistair a drunk or kept him a Warden in your game, it doesn't happen in that DA mythos.
hmmm We'll just have to see, I suppose. If an alternate version of that comic happens, I'm sure it will be mentioned in Inquisition since there's a good chance Alistair will make a cameo again.
I could honestly see Warden Alistair getting a tip from Zevran and going off on the quest because he wants to know who his father really was. Or I could even see Teagan putting Drunk Alistair on the quest in an attempt to get him to shape back up...
All that said, there are also the factors of Zevran even being alive, Isabella not being handed over to the Qunari, and probably some other things that aren't coming to mind atm.