There is an adult skater on youtube who did skate as a kid, then took a very long break to focus on dance (14 years?), but she has learned her double axel and is working on triples as an adult in her 30's. Obviously the dance background is a huge benefit, but it proves that it is still possible to achieve those skills as an adult having NOT had them as a child.
I know a skater who started skating in his late 20's and has an axel and some doubles, which he achieved within a couple of years on the ice. There's a teen at my rink (I thought he was older) who has been skating less than a year and is working on his double axel now... but he is one of those kids who is "always at the rink" and has put in some serious ice time (and off-ice time) and is very focused and determined. His progress has been astonishing, but he's one of those exceptions, not the rule.
I can say, having skated when I was younger and being one of those kids who put in 15+ hours a week, now at 32 I couldn't keep up with that schedule if I wanted to, my body just can't take it. Currently I average 6-8 hours on the ice a week (not counting time spent teaching LTS) with two 30 minute lessons, and occasionally I may push my ice time closer to 10, but I really feel it when I do. I really can't skate every day, I really need a day to rest in between hard sessions. Some weeks I may only get in 4-5 hours in if I can't make one of my normal days for some reason.
I came back to skating as an adult after taking 10 years off - and all of it didn't really come back easily for me. After having 3 kids my body is definitely different, and while some things came back quicker than others, I've continued to struggle with some things that I feel should have come back more easily, and they haven't - jumps in particular, but certain moves have taken more work to re-learn as an adult than they took to learn when I was younger (back 3 turns, brackets, etc). I've had a lot of ups and downs and "why I am I doing this to myself" moments, but I've stuck with it and I've put a lot of work in to having better skating skills now than I did when I was younger, and after 3 years I'm FINALLY starting to see the results of that, but it hasn't been easy.
I had an axel (as well as my 2S and 2Lo) as a kid but I do NOT have them now. I can do them in the harness (as well as 2T and 2F) but something keeps me from really "going for it" off - I don't honestly know if I will ever get the courage to really push myself enough to get that back. I will need to do it if I decide to aim for Gold free, but that requires passing Gold moves first, so I have a while before I really need to worry about it