Normally I would expect the mining concerns to hold onto their profits in BTC. But the recent price drop may be creating a vicious cycle: The more the price drops, the more BTC the miners need to sell to pay their power bills and other expenses. And with more supply on the selling side the price drops lower, which forces them to sell even more off.
IMO, this largely applies only to the larger operations and I can only offer my anecdotal evidence as the contrary. I've been mining since early 2012, and have been gainfully employed for that whole period. My operating expenses are paid for by my normal paycheque, and I suspect that for a lot of miners this is also the case.
I think that some of the more marginal mining outfits are going to be going out of business soon. I figure most miners have based their business models on at least some kind of price growth in BTC, so having it languish like this is going to put some of them in bankruptcy. The network won't be affected much (most of their equipment will be auctioned off cheap to other miners), but the end result may be further centralization.
You're probably right where a lot of the newer participants have evaluated their operations in terms of gained fiat, although the common opinion of longer term miners is to measure the ROI in BTC entirely. As in, the HW costs X BTC and will mine Y worth of BTC. Is Y > X? If so, go for it. Probably a differentiating point is understanding how the individual miner views BTC. Do they believe in Bitcoin as a tech, or are they here just to make money by doing (virtually) nothing?
On the altcoin side it's just as bad - people seem sick of the scams and clonecoins to the point that money is no longer flowing in. A few of the best alts will survive, but it's going to be ruthless and even "good" ones are going to lose to the very best. There will always be room for another coin with a good idea, but the days of eager acceptance of each new alt with a plausible storyline are over.
I would say the motivation behind 99% of altcoins is for purposes of pumping and dumping. There's little to no new innovation in most of them, and as such, trying to accept them as anything but attempted pump and dumps by the creators and early participants becomes harder and harder to accept.
