Via Action Robo we have a partial image from a retailer order sheet, revealing the existence of MP-38. And curiously, it's listed as being "Convoy (Beast Wars)" again! However, this one carries a modifier that works out to the effect of "Legendary Commander", and that might be enough to guess what this is in absence of any photos. Meanwhile, MP-38 is listed at 12,000 Yen and is due for release in late June. Keep reading for speculation!
It's true that there is a comparatively limited range of ways to reuse the Optimus Primal mold, so the options to pick from are few to start with. With the price not having increased compared to the MP-32 release, one can rule out something like a modified version with extra accessories or the like - not to mention that wouldn't seem like it should be its own sequential number. So you're left to look at the "Legendary Commander" title more directly. This is something that Optimus Primal has actually been called - or rather, Beast Convoy has been, when that iteration of the character appeared in the Beast Wars II special, "Lio Convoy In Imminent Danger". This special is notable for the exclusive powerups for both Convoy characters, Flash for Lio Convoy, and for Beast Convoy, Burning
. Pending photos to demonstrate otherwise, a Masterpiece version of Burning Convoy seems the most likely bet for what this actually is. A power boost variant still seems strange to be given a new number rather than being MP-32B or somesuch, but ultimately, only TakaraTomy knows the inner thoughts of TakaraTomy, such as perhaps treating Legendary Commander Convoy (Beast Wars) as being a distinct individual from Convoy (Beast Wars) that was released as MP-32.
It probably won't be too long before a first leaked image of this figure turns up and settles the question. So keep checking with us for more developments as they happen!