If it ever came to pass that Sega needed to sell itself off, I imagine they would choose Nintendo as their preferable buyer, as Sega IPs (well mostly Sonic - but then again Sega is mostly Sonic
) have done best on Nintendo systems, Wii U notwithstanding. The question would then be if
Nintendo would be amenable to purchasing them, something Nintendo rarely does, and has never done with a company the size of Sega.
However Sega is still doing fine in Japan with their arcades and otherwise niche titles, so it's not a situation that would likely present itself unless things got much worse for them.
I don't think so... do you have a source?