Thanks for providing the link. My reading of it is that the NHTSA is pondering the idea of stipulating that weight limit, and that car-seat manufacturers and child-safety groups are suggesting the limit is not a great idea. There seems to be quite a bit of debate about this, based on that story. My son isn't over that limit yet, but my guess is that when he does exceed it he will also have exceeded the size accommodated by the five-point harness. Based on this and on the assumption that laws/regs will still be what they are now, I would guess the safest choice will be to attach the seat to the car with LATCH anchors, then use the seatbelt to hold him into the seat itself.