Very risky move. If you look at how protocol changes in other altcoins have been handled, where has always been a grace period of at least a couple of days. This gives all miners the time needed to update to a newer version.
What is going to happen if you don't get the majority of miners to adopt the new protocol in time?
That said, I've updated my miners (300+ cores) to the new protocol version. Lets hope that we get through this smooth.