It would cover probably 75% of the costs. There is the difference in total cost plus the interest to the bond holders. Looking back now the city really should have jumped at this if it was truely offered.
AEG is a part owner of the Lakers. They own staples. The colts only have 10-13 (8 regular season, 2 pre season, max of 3 home playoff games, but normally 1-2) games at their stadium.
Yes, assuming they were to push the risk off on bondholders, then you have to add in interest and all that jazz, but a team paying for even 75% of the cost of a new facility is not usual. Every once in a while, an owner fronts the entire cost, but more likely, the community is the major contributor. Even Jerry Jones didn't pay 75% of Cowboys Stadium.
I don't know whether they city should have jumped at that offer or not. I think that, on the surface, it's a great offer, but if the trade-off was relinquishing all profits from all events, even non-Kings events, then I can understand why the city didn't like that proposal. I don't know the specifics, but the dollar amount is significant.
Yes, AEG is a part owner, but that's because that's the lease agreement. IIRC, the Lakers don't pay anything to use Staples, in exchange for AEG's minority stake in the team.
As for the Colts comparison... The Maloofs would have been paying almost as much per game as the Colts pay annually to use LOS. Tons of other differences (Irsay paid $100 million up front, for instance), but the dollar amount is staggering in comparison with other lease agreements.