Have nursed through several pregnancies. Have lost my milk totally around ?6 or ?7 months. Before that, I think the milk changed taste almost immediately, because each time I figured out about the pregnancy by the nursers getting a little testy with me while they nursed. Which I found thoroughly fascinating.
Anyway, they all nursed all the way through, and then they all tandem nursed with the new baby.
And the best best best best best best thing in the world is when your new-baby milk comes in, and your toddler, who's been sucking on air for months and weeks and months and doesn't even remember, probably, what drinking actual milk from the breast is like, suddenly nurses and drinks ...
and oh man I do love that first reaction
... the reaction to the sudden reappearance of the milk is priceless, every time.
Don't worry about weaning. If your little one wants to, he will. But just as likely he won't.