My short answer is yes, to e-bikes. This is not a simple integration into trails just yet. There are some things rules and legislation can do to support e-bikes. Private landowners as well as public federal and state trails need to post which trails are available to ebikies, just like they post for horses, bikes, and hikers. There are some things that capitalism cannot police. I read a comment about newbies getting over their heads, buying, riding,and severely injuring themselves or others. Since the technology exists, no one can prevent anyone else from purchasing or using an ebike. This is where common sense has to kick in or , yes, new ebike users will get hurt.
The advantages for the older, sick, or injured outweigh the problems we, as a bike community, will face with idiots using ebikes. As a personal anecdote, I only know one person who has an ebike and he is much older and enjoys the outdoors, but can no longer do some of the things he use to. Several friends like the idea of an assist from a bike, not to burn down the trails but to stay social and enjoy the outdoors.