Taking early August as an arbitrary point in time (actually not completely arbitrary, kind of right after bitcoin started pumping), it's actually down from over 60 cents to around 37 cents today. ETH is down from $2-3 to around $0.80 today. BTS down from about $0.005 to 0.003 today. Dash down from about $3.60 to 2.20 today.
I mean, I know altcoins are pumping and dumping all the time, but I also wouldn't characterize a basket of coins dropping by 40-60% as relatively stable.
Who knows. You can pick different start dates and get different conclusions, though I'd question your particular picks as been pretty far from representatitive. BTS had a huge pump in August and Ethereum announced running out of money (though it was widely suspected already) in late September. Excluding LTC from any basket of alts is pretty questionable too.
Nevertheless I'm certainly not going to claim that alts are doing well in late 2015. They're clearly not.
On other topic, I've heard that Chinese miners haven't been supportive of it (though KnC seems to have quasi-voiced some support). The guy who runs the mining operation in Washington state in USA, which I think is 1-2% of network did come out in support of BIP101 in some reddit posts a while ago I think. But who knows, maybe Coinbase is working with 21 Inc or something and they announce they're working with Intel to build some next gen 14 nm FinFET ASICs or something. I just don't think they'd be putting signed letters out in the public and encouraging other major companies and exchanges to voice support for it if they didn't have some kind of ace in the hole, so to speak.
Here are the stats:
http://bitcoinstats.com/network/votes/BIP101 has effectively zero miner votes. It would require 75% votes over the course of a week to activate. BIP100 does have significant miner votes, but requires 90% over three months to activate, and is nowhere near that (and recently has even been falling a bit). So neither of these appear likely to go into deployment any time soon, but as you say things may change rapidly, especially with BIP101 where only a week of voting is needed.