Aim with new investment is to make sure the money is spent by a guy who can attract top talent to the club.
Strangely, Martinez does have that pull with younger players, but we're in a different league financially now and we can pay top wages if need be you'd assume, so yeah, you could look at Mourinho and Pellegrini seriously in the summer. Maybe. Just depends how it plays out, but if you offer great wages, a massive war chest and the chance to make history at a club like ours, I'd imagine some very decent managers would be tempted at this point.
So in short, we don't have to have the argument about who would replace Martinez anymore. Whoever it would be, it'd be someone of decent calibre now, as we have the muscle to attract them.
It's time we upgrade from the Spanish version of Mark Hughes to a proper manager.