Doing a hard fork requires an exceedingly high level of consensus, as it requires everyone in the network to upgrade (not just miners). Unless there is a security flaw in the protocol, I doubt we'll see one anytime soon.
The problem you are complaining about is an efficiency problem for miners. I doubt you'll get a large percentage of the Bitcoin community to even accept this is a problem. At least in my opinion, it is not, as there are much more scalable solutions already available, such as local work generation.
Actually, it's a problem for pools not miners.
If a pool can't handle larger devices, when large MH/s FPGA or ASIC devices show up - ok we'll have pools failing around us.
It's not the issue of handling a few more higher power devices, it's the simple fact that if people can get these devices, then either everyone will be getting devices that are close to an order of magnitude faster, or most of the backbone of BTC (the miners) will be gone and BTC will die.
Anyone can see there is no exaggeration in that if they have a little sense of understanding of today's BTC network.
Yes there are other suggestion, but this one simply ties in with how things work now ...
Yes I do understand the issues with doing a hard fork - hell look at the mess caused by the way it was done back in April and that was a minor change ...
Ignoring Deepbit (especially since most of his miners don't understand or pay much attention to BTC) I'd actually expect most pools to be looking for a solution already and this solution in itself fits, code and design wise, well and easily into the current design.
It is also a long term solution
If someone thinks 4 billion times the current network isn't enough, then ok add two 32 bit nonce fields (for a total of 3) and I can't see that running out before BTC is completely redesigned some time in the far future.