Not marking as spoiler since this is all speculation, but if the Child does stay until the end either the show has like one more season or its just going to get kinda sad to me they play it that safe.
The Child can only do so much now, he needs to go off and come back when he can talk. Mando now has a very good out of an interesting story thread after he gets the child gone and really besides the people who think the child is too cute I don't see why it would be bad if that character left when its story for now is done. Its like can we take some chances here and there...Mando was a chance taken and it worked why do we can to just stick with the well since people like the child he can never leave the show even if story wise it makes no sense at all. Unless we want a boring show were Mando just raises him then it makes no sense for them to be together after this season it would be selfish and reckless. Mando is a bounty hunter who has the Empire, other hunters after him and pretty much anyone who can make money from his armor.