As a Dreamweaver user and having had a brief glance at Muse, I can only conclude that they are two completely different products. I view the latter as an attempt to allow non-coders to produce a reasonably functioning website.
A fusion of the two, would give me an even more bloated Dreamweaver, at which stage I shall be looking for alternatives.
Flash is dead as a web technology. When Steve Jobs announced in 2009-2010 that Apple iOS would never support Flash, that was the nail in the coffin. In Nov. 2011, Adobe sealed the deal by pulling the plug on future Flash development for mobile devices. The current list of non-Flash supporting devices is much bigger now than it was just 2 years ago.
I agree that Edge Animate is still primitive. Edge tools are evolving because the technologies they use are emerging and not proprietary (owned by Adobe) the way Flash was.
As far as MU & DW, I see no way of combining them. These are totally different products aimed at very different users.
DW is professional level software for people who care about web standards & the quality of their product. DW can be used to code just about anything from mobile apps & responsive layouts all the way up to enterprise level CMSs. With DW, you're limited only by your coding skills and imagination.
MU is consumer level software aimed at hobbyists & non-professional web builders. It's very appealing to non-coders. Unfortunately, the trade off for all that "ease of use" is bloated, convoluted code that even experienced web developers find hard to work with. Finally, with MU you're limited to a handful of templates & widgets. If you need something more, you're out of luck. Of course, that may change over time. We'll have to wait & see.