The more important question, regardless of age, is how much are you willing to sacrifice. The people that push the boundaries are the ones that devote their lives to it. Going to the the gym after work aint good enough, and unless you are a trustafarian, RedBull doesn't sponsor weekend warriors.
Of course the low hanging fruit has been eaten, and you are ...
I agree 100% with the answer of @endolith, but will add one point. If doing something "worthy of mention" is of great importance to you, try for an age record or a disability record. People take great pride in being the first X climber to climb Everest, where X ranges from blind to amputee to over N years old to whatever.
Maybe you can pick a ...
I've been thinking if it is possible to achieve anything (worthy of mention) for someone who started at 
Lee Sheftel started climbing at 33, climbed 5.14a at 59 and 5.13b at 68
Margarita Martinez started at 34, climbed 5.13d at 58
Akira Waku started at 35, climbed V15/16 at 48
Juichi Ogawa started at ~47, climbs 5.12d at 72, was better at 69
Are these &...