well i tried to answer about general fork/split of the blockchain and how the mining will work. and this falls under the things they have changed about mining.

also a thing about forks like this is that they become very unpredictable. in the first day if hashrate is extremely low and they readjust difficulty, hashrate may go up suddenly and cause another kind of delay. as in 1000 blocks mined in 1 hour. (see what happened on SegWit2x testnet when someone redirected a huge hashrate there and mined a lot of blocks!)

p.s. there is also 51% attacks to expect...