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.