Originally Posted by Clipper801
if AC will add a line in bold on the upgrade certificate that "confirmed upgrade reservation is not guaranteed and may be cancelled at the pleasure of AC at any time with or without cause." While this may not happen often, it has known to have happened.
I also think this should be stated--either that, or put a word other than "confirmed" on the itinerary/PNR/wherever this information is kept for segments in I class.
If you're confirmed in Y or J on a paid ticket, and you're denied boarding/downgraded from J, you'll usually be compensated in some way. The word "confirmed" means something in those contexts. If you're "confirmed" in I, there is a chance--however small--that you will not be flying in J, and you may not be compensated if that happens.
Whether AC is being unfair to those few FFs in I who do have to downgrade, particularly after paying for a Y or M fare to get the instant upgrade, is a different question. But if AC makes it clear that upgrading to I class is subject to space availability, and that space availability is not only a function of the literal availability in I (ie, may also be a function of aircraft downgrade, last minute paid J walkons, etc.), then the FFs who lose out won't have much to complain about.