What is your question?

How long does a five year old stay five years old?

That may be how long those tiles will be appropriate.

Those are fabulous tiles. I would like them in my house.

I think keep the bathroom permanent decor neutral and add decals that suit the age of the kids . easily changed and if every resale is an issue remove them and be done. I might do those tiles in alaundry room for a bit of fun

I agree with Rho. Beautiful tiles.