a forced global upgrade across thousands of independent entities, in two weeks.
Yes, two weeks is rather short. Two months would have been better. I suspect that the 75% will be reached very quickly, or never. I suppose that Mike was afraid of some PR counteroffensive that would convince many 8 MB adopters to switch back to 1 MB, if the grace period was too big.
After all how hard can it be to force everybody to adopt the new bitcoin, even though they dont agree with it?
Once 75% of the miners have agreed to switch to 8 MB, agreement is irrelevant. The remaining miners and the major services will choose to switch before the 8 MB limit is enabled, even if they didn want to, otherwise they will lose money. They will be aware of the event and capable of upgrading in time.
But even you agree that there will be an altcoin created out of this and that altcoin will have nontrivial value, probably more than LTC, certainly more than NMC.
No, I don't agree with that.
Litecoin is a functioning coin, that non-experts can use as easily as bitcoin, with no confusion. It has its own exchanges, a large user base, etc.. (It is even used by bitcoin arbitragers, I read somewhere, to quickly transfer value between exchanges, due to its shorter block period.)
The "1 MB bitcoin", if it survives at all, will have a very long block period, a huge and growing backlog of unconfirmed transactions, practically no services and exchanges -- and very few people will know how to handle it.
Indeed, if the 8 MB sizelimit prevails, its miners may find it worthy to put some of their hashpower to the task of jamming the 1 MB branch, to minimize confusion of clients who failed to upgrade, and to prevent its use for scams.