yep and all the big boys need to do is stand pat and do their best to limit network growth under 3%.
I think you're trying to talk them into something that's good for you, but bad for them.
Oh they can replace a 1 watt miner with a .8 watt miner then a .6 watt miner but they are building there own so they do not need to sell much just a little bit at a time.
Why would they replace a miner that's profitable (on a sunk-cost basis, which is the proper criterion to use) with a new one? If you've already paid for it, the logical thing to do is to keep it running until its revenues drop below electricity and hosting costs. Buying new hardware makes sense if you expect to recoup your costs, which are much lower if you produce your own miners and already have your mask set. If anything, if they bought new hardware, they would be running it in parallel with their old hardware, unless they ran out of space / power in their data center.
As for selling, I don't think we're ever going back to a situation where miners hoard a substantial portion of their mined bitcoins. Bitcoin mining is a fiat game, and the rational thing to do is to sell it all.