I don't think Gearbox should make it. Not because I don't think they'd make a great game - they would - but simply because fanboys would hate it before they saw a single screen.
Half Life (2 Episode) 3 has been hyped into oblivion and it hasn't even been announced yet. Hell, no one has even confirmed that it might possibly someday enter consideration for potentially existing eventually. If Valve, a company only slightly less popular among "core gamers" than self-diagnoses of asperger's syndrome, releases info on a Half Life 3 that isn't quite to everyone's liking, gamers might give them the benefit of the doubt. If Gearbox releases images of a Half Life 3 in which Gordon Freeman has two strands of hair out of place and a slightly longer beard, people would be screaming, crying, calling for boycotts and setting fire to copies of Borderlands within the hour.
I like Gearbox, I think they do great work. But Valve could release a "great" Half Life 3 and it would be declared the second coming of Christ in digital form before the dust settled at GameStop. Gearbox, on the other hand, could release an actual digital second coming of Christ under the name Half Life 3, and people would be declaring it Duke Nukem Forever 2 before the GameStop servers recovered from the mass exodus of pre-order money.