I think your last paragraph about cultural value could be debated, whether you or I regard a bunch of Finnish ice-skating dancing girls dressed in corporate colours singing ABBA songs (I might have made that up) to be of cultural value doesn't mean someone else doesn't think it's the greatest artistic movement of the 21st century. There was a non-stop program of stuff at the performance venue that I had no interest in seeing but using numbers quoted on CMR it seems in the first 60 days 450,000 people disagreed with our view. No one is going to debate that the opportunity for local Shanghai culture was rather limited to say the least (I have no idea about the facts here but would suspect that close to zero may be a better estimate) however it was a World Expo, not a Shanghai one and the intent was to bring performers from all over the world to China. Shanghai does now have a quite incredible performance centre that will remain although again, it is unlikely to be of much interest to local bands but it does seem that some of the first events to be held here post-expo will be popular music - Wang Fei and Jacky Cheung. Not my cup of tea but all the tickets have been sold and both are doing a long series of shows.
So after a whole load of possibly not relevant to your point comments some observations purely from my pov on impact on the local music scene. Disclaimer number two, I have been traveling like an idiot for the past 7 months so didn't get to many shows during that time.
1. Where did all the great local bands go? If I think back to last year there were weekends where choices had to be made.
2. There were at times this year entire weeks (my perception, not backed by fact) that YYT seemed to have overseas acts with little or no local support bands. I am all for overseas acts playing, big names bring in people who otherwise wouldn't go to underground venues, what does bother me is it appears that there is little benefit to the local scene.
3. There has been(?) a move of focus from the centre to the suburbs / closer to the universities by local bands.
4. In contrast to the local acts disappearing there seems to be an increase in expat bands (I don't have anything against expat bands btw , just an observation).
5. Mao seems to have be moving to techno and parties and has close to given up on promotion or maintaining their site or their douban pages.
6. YYT seem to be doing a monstrous amount of regular maintenance to their web site (that is irony by the way).
I'm not a sociologist but there does seem to have been a big change and as I haven't been propping up the bar at YYT so much this year seems even more pronounced. There are a load of factors that could have influenced this state; the need to make a living and the stupid cost of living in shanghai, personal conflict within bands, relationships and the pressure they can create, limited options for performing, limited returns, the impact of having to play late and lug your kit back and forth all the time, limited options to rehearse and record, seasonal trends, etc.
All the above however existed in the past, these are just the normal strains and constraints that local bands face here and anywhere to varying degrees. I don't think it a huge risk to suggest that the one big difference this year was down to the direct and more so indirect effects of hosting Expo. You've listed and recorded some of the more bizarre events that have put serious pressure on local music like the YYT closed/opened/closed/maybe open/hanging in there stubbornly mayhem that various outside agents created. The general air of excitement that existed prior to expo seems to have been, whilst not crushed, definitely deflated and replaced by a sense of nervousness and apprehension. Under those conditions it is hardly a surprise that things have slowed down and hard working artists have decided that things were way too hard to bother.
It remains to be seen what will happen now we are back to normal(ish). As you pointed out it hasn't all been doom and gloom and it is clear some pretty good things have happened this year. In particular as it wasn't mentioned in your post the creation of the new label Zhu Lu He Feng that pulled a few of the local bands together, got recording and started doing University and other gigs. As a non-insider my view is this year was a (big) hiccup in the maturation of the local music scene, what I have seen here is a pretty awesome little scene with some incredible support driven by some really talented and committed people. My hope is we see not just a recovery but a post-expo hangover reaction that sees local music not just return but return with a bang. And what better way to celebrate the end of expo than the White Eyes show, I really can't think of a better riposte by indie music to the past 6 months of Expo's mediocrity.
Final note, way back before the big event I replied to one of your posts about expo suggesting that rather than a negative impact there would be a small positive one. I was absolutely, completely and utterly wrong.