My other thought is that, quite possibly, any country home they have will probably be an interim arrangement till the end of this reign only. When Charles is King, I suspect he will leave his beloved Highgrove to the next Prince of Wales, who in turn might let Harry use Anmer. Clearly this is speculation on my part, but I would welcome your thoughts.
The question is would either of them want to? My understanding is that the couples have their own circles near their weekend homes. The Cambridge have their social circle in Norfolk, and seem to be fond of that area. Whereas the Sussexes seem to have a fondness for Cotswolds, which is close to Highgrove. As of now, I’ve seen no indication that Harry or Meghan are particularly fond of Norfolk other than Christmas with the family. We can talk about what makes the most sense logistically all we want, but the wishes of the couples in terms which area they live in will also play a part. But I agree that the current situation is only temporary. One of the considerations is probably the timing of the next reign and what will happen in the next few years in terms of space.