True, I did say "if" though. But it makes you have to decide what you "want" to be and work from there.
Personally, I think it would be a little too close living next door to each other. There are all sorts of pitfalls, not least children. If Harry and Meghan have children they will be raised as befits their future. So, look to Beatrice, Eugenie, Louise and James who all actually "have a private life" to live that is not royal, will not include overseas diplomatic trips, etc.
All these necessities to the Cambridge's will be curiosities to the Sussex children and having them live right next door to each other will only serve to highlight to parts of life that royal kids are not fond of. So, having a little distance would be a practical move for both the Cambridge's and the Sussex's which is why I tend to think that Harry will be treated the same way as any other royal second and third, namely Royal Lodge and Bagshot Park.