Once the market develops I would expect motorcycle shops to happily sell/service electric mountain motos with throttles and pegs or throttles and vestigial pedals. Keeping things looking electric pedal assist mountain bike-ish enough to avoid getting noticed too easily. LBS can keep their service options strictly pedalec/moped or not it won't prevent the shift to throttles.
Once you let motors on the trails it is hard to manage the obvious changes that will happen to the tech. It's not like it's practical to have cops at the trailhead inspecting machines for compliance and issuing tickets. In the past it was a social pressure thing. Show up on a motorized contraption and the mountain bikers/hikers would stink eye you into submission.
However, once you let in one type of motorized machine the people astride them don't really have the moral authority to say "Hell no!" to someone else on a similar, but slightly different machine. While I would have been [and was] "that guy" and told e-bikers the can't ride these human powered trails I'm not going to spend my time policing which variety of electric motorized dirt bike/e-bike/moped is legal and what isn't. If we as a community are now saying partying in the forest with motors on biking/hiking trails is cool then so be it.
I will laugh really really hard if an e-biker ever sits down next to me at the brewery in Cumby and complains bitterly about some dude on an unrestricted electric bike with a throttle shredding uphill past them. Life can be cruel sometimes.