It's the same general principle as why they haven't done a G1 style Soundwave, the alt-mode is implausible for a modern toy. Grimlock is sufficiently iconic that I can see him being an exception, and MP Rodimus can sort of pass for a real vehicle if you're a myopic pyromaniac, but G1 Galvatron traditionally transforms into something like this.
It's not impossible and I'd love to be wrong, but given how few and far between the MP line is, how costly they are, and how they love to milk the repaints I'm not holding my breath.

As for BW TM2, I love the toy to bits but there are quite a few improvements an MP could make. He could do with a bit more poseability in the neck, tail, and wings, poseable beast mode claws, and above all covering up the head above his tail in beast mode. And of course there's the accessories to dream of: an official pair of Golden disk accessories, the energon knife he 'operates' on Rampage with and/or Rampage's Spark torture cage-dooley, and most importantly his rubber ducky. Rubber Ducky deserves an official toy dammit!
Even then I'd think if HasTak ever does do a MP BW Megs they'll do him in T-Rex mode, either TM or first Earth alt-mode.