It all depends on what form this fusion console concept comes in. If Nintendo are genuinely rolling their handheld and home console development into one then their output will be very significantly improved, that alone will diminish reliance on third parties (that ship has sailed and will not return). At the moment, they simply don't have enough internal output to support two systems. All Nintendo's games on a single console though, that's a completely different prospect.
On the hardware front, give up the idea of a needlessly small and efficient console too because that is simply adding cost and pandering to a market that doesn't even care about home consoles any more (My power bill does not care if my game system uses 30 watts or 300 watts) Give up on expensive peripherals and put that money towards developing a powerful, and easy-to-develop-for, yet affordable, console. At a minimum start paying a little more attention to the western markets and standard requirements for online infrastructure.
If they do these things and throw in a little Nintendo weirdness just for good measure, absolutely they can be relevant.







