I remember recently there were brief rumours of a partnership with Toshiba to release a console and take Sony head-on. If they kept it a Japan only console and forced all their Japanese IPs to that platform, I believe the titles they have (RGG, PSO2, Miku, 7th Dragon, Persona) would have been strong enough to keep the platform afloat. Ooooh and ports of their recent arcade hits would definitely be household console hits. Damn Sega should get on that already. If ever Sega Console Cool was riding a high, now would be the time with their legacy consoles being anthropomorphed twice over.
Sadly, none of this would work here in western markets. That, and I have no confidence that SOA can do anything with a new Sega console.
For global appeal, it would have to be a handheld. Sony slammed the ball into the pavement with the Vita. Sega could definitely take over with a handheld. Give it smartphone abilities (android) and it will already have a huge 3rd party library established.
I dream of either scenario constantly. I'd sell whatever PSFail/xbone/Pii-U consoles I have and import the hell out of a JP only console, or I'd toss my iphone into the ocean if there was a Sega combo handheld.