I don't think hes going to gas. I don't think hes going to throw punches just to throw them. MMA is some serious cardio shit. I think maybe he will take damage AND be getting tired BUT I don't think hes going to straight gas from throwing punches in 12 rounds.
If Floyd senses him slowing and he becomes aggressive, he can put the combos together to fold Conor. If Floyd never becomes aggressive though I don't think Conor tires. Its going to take damage.
I agree with you on most of your points but disagree on a few others. Here is how I see it.
1) The draining part of cardio in MMA is grappling and clinch work. Two things that Conor rarely encounters in his fights. Conor has gassed in the two Diaz fights before any grappling exchanges. Thus, it is
likely that in the same 10-15 minute time frame with heavier gloves and a faster pace than Nate's, Floyd will get Conor to gas.
2) While Conor will not throw for the sake of throwing, he also cannot afford to be conservative with his punches. His best chance will be to be aggressive early on, as landing a counter on Floyd is nearly impossible.
3) Floyd will, and has in other fights, spent a lot of time digging into the body of of his opponent which will drain that gas tank even faster.
4) Floyd is very good at landing quick ,but effective, shots while moving backwards. This has become his staple in the eyes of many. This will neutralize the danger of Conor's pull counter while still piling on damage and pushing the pace.
That is how I see it anyway. I don't see a scenario where Conor doesn't gas personally. Through my experience while MMA can be exhausting, the stand up is actually not that bad. The damage in the clinch (knees, elbow, takedowns, slams) is what kills your cardio. In boxing the stand up is much faster pace since there is no danger of kicks and a closer range to work with.
If Conor underestimates boxing's toll on his cardio then he will shrink his chances of victory even further. But hey, I could be wrong. You never know until fight night