How do you know how long this will take and what the consequences will be in the meantime? Define extended period? As far as I understand it, this is going to be messy as hell and even if the old chain is sold into oblivion in 72 hours, the PR damage will be permanent and who knows who is going to get scammed or which transactions will get completely fucked in the meantime.
The main reason for a short life of two paralell coins, is that liquidity the the all importan statistics. Two coins almost exactly the same is totally unstable. It has to lean to one side or the other, then the one with smaller popularity will take the liquidity hit and land hard.
"As to what will happen if/ when there is a hardfork:
Currently MultiBit Classic and HD both will follow the chain with the most work done in it.
Thus in a hardfork all the existing MultiBit code will follow the 'winner'. This is how the normal one or two block forks (that occur reasonably frequently) get resolved so it should just be the same but on a larger scale.
Both MultiBit Classic and HD connects to Bitcoin Core and XT happily and they should work correctly with larger blocks. The bloom filtered blocks Core/ XT send back to MultiBit are the same - MultiBit is agnostic about connecting to Core or XT."
https://bitcointalksearch.org/topic/m.12154185
So all over in about twenty minutes or so.
That is just one wallet... Everyone needs to have a similar feature already built into their systems before that majority hits. At the current rate of adoption that looks to be less than 3 weeks away.
I want every wallet provider, electrum, mytrezor, mycelium... to declare where they stand. There should be enough time, no rush.