I echo what many stated here, that this thread is inspiring.
As someone who is more "innately" an improviser and cannot read music, I have focused this year on technique (so I don't sound like I'm smashing the keys). I also quested to be more proficient on all 12 keys, instead of just "jamming." I also for the first time decided to take playing piano seriously.
So whether we're sight readers, or improvisers or both, there is limitless amount of things to learn, which at first can seem daunting, but is actually exciting since you'll never be bored.
At the meta level, I also look at the "am I too old to do X," I think of it in very organic simplistic way: I either apply my brain towards something, or I'm just inert. The latter is never conducive, but is often a limiting thought we all have at times. The analysis paralysis can lead to inaction as we then feel discouraged, etc.
So to reiterate, in my own head: "I'm either going to get better, or I'm going to regress or be stagnant."