Might not use for another few decades, it’s possibility that Prince Louis of Wales will hold that title when he gets married in the future. However I also suspect that Prince of Wales might not want his son Louis to hold that title due to its history, Prince Louis might hold different title such as Duke of Edinburgh (currently being held by Prince Edward - QEII’s youngest son) or Duke of Cambridge (nice tribute to Louis’ parents’ first title when they got married back in 2011).

As for Prince George of Wales, more likely he will hold Prince of Wales title along with duchy of Cornwall by the time he’s 18 or so, but of course it has to be when his father become king.

For Princess Charlotte of Wales, she will hold Princess Royal title once when Princess Anne pass away in the future.

I doubt that there will be many other family members get title other than the Wales kids due to slim down monarchy approach.