I’ve been running consistently since age 18 or so, but only competitively since 26. Jeopardised some of that time though through stupid decisions - mainly anorexia - and bad training, some injuries. Got it together a bit more around 27-8 including training more rationally and having a coach but still struggled with my health, mainly low testosterone and lack of calories. If I turn it round now have I got a chance to run well in my 30s or will age make me go downhill anyway ?
Good is of course relative. You probably will not be World Class but you still can do a lot of running. First Marathons and then Ultramarathons.
The possibilities are almost endless.