I would think this could be the way TC's will go to make it easier for racers using LiPo's.
The E4 as well as the JRXS Type R are very similar to the Pro3 in basic layout. But both have made great improvements over the original Pro3 design.
The CF Pro3 was what the car should have been from the beginning. Going plastic tub style almost look like a downgrade from the CF Pro2!
I remember reading that HPI went with the Pro4's shaft design because that was the hot setup at the time with the TC3 having alot of success in racing back then.
The Pro3 was what got me back into R/C and would love to see HPI make an updated version