I think you are right AC*SE--there will be more open seats but the question is whether AC will release them as freely as they have in the past (ie. will they institute even more capacity controls).
I have never been shut out of an upgrade since becoming SE (that I can remember anyway) even when I have changed travel plans and was standing by on oversold flights.
I am taking a wait and see attitude but my prediction is that I am going to see less upgrading being successful at time of reservation and more waiting at the gate for the standby upgrade. I hope not but with less overall flights on some routes, there will likely be a crunch somewhere. Elites will feel it even more than Super Elites as they will be less successful even in the standby upgrade situation. If they have paid the extra fare in anticipation of being successful and then are denied repeatedly, there will be significantly more anger than is being expressed here.
Over the longer haul, I think you will see people coughing up the extra $100 or $150 to get a V fare and the upgrade though. Delta has similar discount fare upgrade restrictions in the US but doesn't seem to have trouble attracting customers despite all the protestations (and there were many on this board) against the L fare policy.
Unless service really deteriorates, the extra leg room and service is worth it on transcontinental flights but doubtfully worth it on Shuttle type flights.