Taking into account Janeway's actions in Voyager's "Unimatrix Zero" and the other Janeway in the "Endgame", it is possible that Borg has been destroyed as a cohesive "nation". It is unclear if the Unicomplex's destruction was caused by the neurolytic pathogen or was a quarantine attempt of sorts, but USS Voyager also destroyed the transwarp network which was another huge factor of the Borg superiority. It is unclear how much of a network, though. It all depends on the interpretation, of which one possibility is 100%, as it was The Queen's responsibility to maintain said network. But then again, in 2373 (technically 2063) Data destroyed Queen the first time, without, seemingly, much impact on the Collective.
In addition First Contact proves definitely that Starfleet has the means to effectively resist the Borg to some extent, so expectation is Alpha Quadrant will survive the Collective just fine.
As mentioned, I'm not sure that The Borg Collective exists anymore, but there are definitely cells of the Borg "species" here and there, consisting of beings freed from the Collective before the Unicomplex's destruction, scattered across all four (definitely three, not sure of Beta, but I think Borg had a transwarp coundit terminal there, too) Quadrants. It's possible that they, along with The Voth (as pointed out by Valorum), Species 8472 and possibly equivalents of Species 116 (sufficiently advanced to resist Borg on one-on-one basis) will successfully resist The Collective. After all, USS Voyager surveyed less than 10% of Delta Quarant, so assumption of above is more than reasonable.