I'd guess after ten years your strelitzia is just about breaking out of its pot. Although they flower best when their roots are restricted, like any perennial they run out of steam if not divided and fed properly. I'd wait until next spring and then divide it into several smaller offsets and pot them into good new compost.
It may take a year or two before they come back into flower, but then they will be like new plants.
I think mine is probably getting into the same state as yours as it's been flowering well for eight years, this year with more flowers than ever, but it's so crowded in its pot it's looking rather exhausted!

As far as I'm aware, they don't get "too old to flower". What they do get, though, is potbound, so if yours is in a large pot already, next time you repot, split the plant so that there's more root room for each one in the pots.

Snap, Bertiefox...