When I read your question, I tried to think of a track where I've had my knee down at over 100mph. And I can say with a fair amount of certainty that's yet to happen. I think if you have to get your speed up that high, you probably also have to "exaggerate" the turn to get a knee down. In other words, I picture someone really stretching just to get a knee down, not because it's what you need to do to get through the turn.
In that kind of scenario, I'd say your warning before traction loss is going to be slim to none, since you probably won't be in the proper position on the bike. A 100mph high-side where you could be waiting 30+ minutes for an ambulance to arrive is a rough way to find the limits of the relationship you and your tires have.
I'll give the 2340987th nod to doing a track day.
