I think e-bikes are bringing a lot of people to cycling who would not be riding otherwise. Some for transportation, which IMO is a good thing - one less car.
As for sport cycling, we had a older cyclist show up regularly to a group TT. The group actually liked having him out there, riding a constant 25 MPH. Nobody considered him a competitor, just a target either to chase or stay ahead of.
I can see somebody screwing up a group ride, particularly if we get stealthy e-assist bikes.
One consequence of e-bikes will be more and more MUPS with posted speed limits.