I’d say it’s possible, and in fact recently spoke with a 70-something lady who learned to play the piano in retirement.
It’s a big project though. On a par with learning a whole new language, perhaps. And my hunch is that you need a coach, ideally.
But, people do amazing things.
Personally I learned as a kid and even had a Saturday job playing for a tap dance school at one stage. Once in a while these days I’ll stroll over and tickle the ivories, but am rustier than Granny’s mangle sadly.
Get stuck in. If you fail you fail but you’ll never know if you don’t try. And besides. With modern technology you could learn the rudimentary stuff then go onto GarageBand or whatever and start tinkering and do something pretty cool. Few years down the line you’ll be rocking up in the techno tent at Glastonbury with your new tech-house massive. Enjoy the journey 
I preferred the immediacy of the first draft - yes there where errors but it conveyed an urgency of expression
Where?
That’s the thing I never really understood with a lot of folks that played. Some could replay tunes they’ve heard note for note but if you asked to write something, they’re pretty stumped.
Mrs FP is a bit like this. She’s brilliant at piano and if you put a piece of music in front of her she hasn’t seen before, she’ll play t will in a couple of goes but I used to try and get to jam some stuff with me and she was just lost.
There’s learning to play and learning to compose and they are two different things.
My wife is a great pianist, learnt from an early age. Studied music at uni then post grad. Became a session musician and music teacher. She can read music and play more instruments then I can actually name. Daughter inherited the musical talent too.
Me? I can’t even hum a tune that others will recognise. But then, I can walk through a doorway without hitting both sides of the door frame. Neither of them can. This great skill of mine will stand me in good stead one day!
Was it not Mozart who couldn’t read music - I’ve definitely just made that up, ha! off to google … hang on 
… no - Hans Zimmer, Elvis Presley, Bob Dylan, Eddie Van Halen, The Beatles, Eric Clapton … crikes. Losers the lot of them
Get some kind of keyboard before the grand paino, and just go for it, if you don’t try you’ll never know 
You should be on Twitter
A friend of mine started learning in his late 50s. He got himself a half decent keyboard and, after some difficulty, a teacher. He’s up to about grade 4 now. He finds it quite amusing that when he goes for the exams, there’s him and a load of teenagers 
Worth pointing out that he has retired and practices for about an hour a day. He’s basically turned himself into Hugh Grant in “About a Boy”, breaking the day up into chunks to fill his time. He’s also very focussed when he puts his mind to something, I suspect that’s fairly critical to learning an instrument.
Little Cobbie, now 9, is just about to start learning guitar. I’m told it’s easier than most other instruments and I can hold out some hope that he’ll develop into a rock star and pay for my retirement 
I’m semi-retired and therefore have a big hole where work (and more recently, looking after a now deceased elderly relative) used to be. I have the time and if I get that spark, I do tend to obsess about things. I’m looking for something completely different I can get into that takes me to new places, meet new people and to learn new things. Much like triathlon did for us in the early 2000s.
I keep meaning to take up old hobbies like motorcycles, running and the suchlike but can’t get enthusiastic about it so maybe that’s all in the past.
Maybe I’ll get a keyboard and have a bash. Christmas is coming, I’m sure I can put it on my list for Santa.
