Everyone theorising about how the next Xenoblade will be the cast of X and numbered games meeting or some gay avengers shit (they don't even have the same art style)
Realistically it's just the planets joined together at the end of 3 and it was happy ever after and a send off.
Ending of X shows the character heading towards this planet too. Towards a happy ending. It's a send off for them too. It closes their story.
Next Xenoblade will be a new beginning. That's all it is. Anybody else trying to make up that it's some grand vision of X and numbered games joining together to become Xenoblade 4 are reading too into it.