Just a few things:
Other RTS's don't have this problem to the same extent, since if the games outcome is know.. more or less everyone leaves, and rolls a new game.
However in DG (& dota for that sake as well) are pretty much the only RTS's that rage quitting is considered a shameful act.
With this in mind, it would be interesting if this problem could be appraoched in a similar fashion as other RTS's ..
So with this in mind, I think changing win conditions will change the perception of the expected game length... people may be more inclined to head out and start a new game, if all of a sudden we're up against team of AI.
Situation: Hop into a panth game, CURRENTLY if theres connection issues, people drop, w/e say it 3v3, and quickly turn 3v0 within first 30 seconds (damn quitters) .. Now I would have to finish this comp stomp before i cna have my "win" and my favour .. (and of course most importantly, the forces of light also get their favour!)
Now this situation, should it be replaced with an ability at the end there for the game to recognise that im more or less going to win (i dont recall ever losing to AI .. at least panth lvl ai), allow me to leave the game, and start finding a new one, with the system accepting my win/favour.
This would allow turn around to be increased, allowing my games per hour to go up, it would also mean I may not need to achieve the required win requirement, but maybe all the other heroes left. This could potentially have a side effect on panth macthes were people disconnect on launch, and then cause the panth game to START with ai ... then the game could be considered an auto-win or somesuch ..
The ultimate change I think comes down to making me not too concerned with people quitting .. making me able to get to the end of the day with more time played, in game, with real people.