why would he go abroad to study AFTER becoming a trainer? Or use "smell you later" after RBY, which he's abandoned using as of GSC?
Don't forget that Gen 6 and Gen 7 takes place in an alternative universe where mega evolutions exist and events have been altered. The Blue mentioned in X and Y, as well as the Blue seen in Sun and Moon, might have a completely different history and personality than the one from Gens 1 to 5.
Come to think of it, since I have a sneaking suspicion that this new remake might take place in this new universe, it would not surprise me, should rumors be true, to find Blue in this game is just a cocky but still good hearted kid who's traveling with Red on their own Pokemon adventure.