Obviously nothing is guaranteed, but by that time the Europeans saw the last of the Palaiologoi as a curiosity and nothing more, and their imperial title as a fun plaything. I doubt that that would much change just because they held Montferrat, and Montferrat itself isn't a good breeding ground for the reconquest of the old empire or the establishment of a new one. I will say that, while there is no reason why posession of Montferrat in and of itself would change things, you could have one of their rulers be an excellent speaker who is able to gain considerable interest in the cause of the empire's restoration. There were serious attempts to restore Thomas to the throne OTL, but they failed. Perhaps you could have this fellow drum up some more interest and make the crusade more successful, but that is still a tall order.
The other possibility is to have this tiny imperial enclave survive until the collapse of the Ottoman empire. At that point, rather than proclaiming a kingdom of Greece, the Greek nationalists might proclaim the empire restorred and invite the imperial Palaiologoi to be their new rulers. As an integral part of their national image, that might make the Greeks more hard line about reconquering Constantinople, and make the west more interested in helping them achieve that goal, but the butterflies from a 15th century PoD might remove the Ottoman collapse alltogether, so it is hard to say.
Russia claimed to be the third Rome because their Tsars up to Ivan the Terrible were descended from one of Thomas Palaiologos' daughters, so perhaps you could have other nations marrying the Palaiologoi in order to justify pretensions to being a new Rome. Of course, that could be an interesting way of legitimizing the Holy Roman Empire to an extent.