The life expectancy was probably more like 35 years, I would guess (and I really don't know), so that's even more generations.
Still, I don't buy a migration from proto-Alaska to proto-Patagonia, or even proto-Palm Beach, over a 1000-year period. Some of those bands which are nomadically wandering around are going to die-off, for instance. Others are going to find a comfortable valley and, not knowing that an even more comfortable valley is on the other side of that high ridge, will stay put. I'm not convinced that the population pressures are sufficiently high to prompt migration out of that comfortable valley.
I don't have a good hard argument yet. The Clovis hypothesis just never has smelled quite right.
Kennewick Man (9,300 years ago) as well as Spirit Cave Man (9,400 years ago and the oldest mummy ever found in the Americas) died in their mid-40's.