I'm sorry to say that I strongly suspect that the chances of anything happening between you are low.
This is my take on the most likely scenario as to how this will play out:
After a 10 year relationship, he will be like a kid in a candy store - particularly bearing in mind that 10 years ago, internet dating was not common. This will be a new toy for him amongst other ways of dating. He's like to be dating up a storm very shortly, casual and all for fun.
He's unlikely to discuss any of this with you - now he knows you like him - for obvious reasons (not wanting to hurt you and/or blow up his back-up ego stroke plan) and you will grow apart. He'll periodically check in with you to keep the flame alive in you - just in case.
Meanwhile, because you like him, you will at the back of your mind have this little brain weevil worming in and out of your conscious mind singing a little background tune he likes me. You will be hoping something will happen between you and won't really be interested in anyone else. You'll try to date but nothing will really stick because you are hoping...hoping...hoping.
Then one day, amongst all the casual dating, he'll meet a woman he is really into and get very serious very quickly.
You'll be utterly heartbroken and alone. And he'll skip on his merry way into the sunset.
TL:DR: Don't wait for him. If he really liked you, you'd be together right now.