I'm sure some people will say that SegWit/BU must be activated hard way even with risks chain split, community split, price crash or other else.
I also think that we might have to think that option, especially if tx fee become very high, there's altcoin which have at least 50% of bitcoin market cap or when the community tired with drama.
I wouldn't mine too much, as I recently wanted to pay something rather small in Bitcoin and was discouraged by the insane fees and I really think something must be done about this, or some altcoin will take over at some point.
But an advance notice would be nice: I have some bitcoins in trading platforms, and I'd prefer them to be in my wallet if and when a split happens...