I think you should try and release it.

You're hugely underestimating both the interest and how much money you could make off something like this.

To put in perspective, when I browse Trainerroad's active user list per month, it's over 1000/month (I can't even count them since there are so many) whom are paying $10/month, and not just during winter. (I checked during summer.) That's well over $10k/month and could be even 5x that amount by my guesstimates. And they have almost zero competition. (There are two other pieces of software out there - peripedal and one more.)

Your product looks great and you already have a working prototype. Just finish it, and beta it for free for 6 months to work out the quirks - that's how TR got started from a homegrown project, and now they're fully legit and don't even need to advertise.

Get the beta out, on a forum, and you'll really see how much constructive feedback and encouragement you'll get.