I don’t think your worries are completely unfounded, but lots of sons remain very close to their mothers. My son is single, so our relationship is pretty much unchanged, one of my son in laws, remains very close to both his parents, and a man I work with is the same.
I would say, enjoy your lovely boys, our family is girl heavy, and the boys have all been a real joy, so lovable and affectionate.
It’s inevitable as they grow up, that it’s harder to stay close to your sons than your daughters, but it’s not impossible. I’ve got a friend with three sons and three stepsons, and she used to them all off on camping trips, they all loved it
Little boys are lovely, you’re lucky