In 3rd season as Spurs I brought Lorenzo Di Silvestri as a RWB, played brilliant for me.
Although, as for Sagna, 29's not that old is it!? haha.
Suppose it's the perfect chance to bring in someone really young (I'd suggest Serge Aurier as well) and bring them through giving them occasional games.
On the whole I find that there aren't anywhere near as many good Wingbacks as their should be though, especially not young players.
I bet the regen ratio of "great" strikers to "great" wingbacks is about 10:1!