I believe a virologist on BBC a while back said similar. If it mutates it’s likely to become less deadly rather than more so.Yes - in general it's not likely to mutate into anything more deadly once its' successful, as that'd mean it'd kill quicker and have less time to multiply.
That said the likelihood of it mutating and becoming a non-issue anytime soon is pretty much nil. They are generational evolutions and can take years.
EDIT: Before anyone jumps down my neck, no I'm not an epidemiologist obviously but I've read a lot last few months as I'm sure a lot of us have!!!