Why not! You are in excellent condition and if you can wrangle the time, you have a opportunity. As you are into endurance sports, you won't have many surprises on your physical ability. The journey begins with the first step…
As I read your thread, I had some first impressions. No show stoppers, just impressions on what you might find different from racing:
I agree with Roger– you will be in more danger in a car on the way to the trialhead than on the trail. The AT is long and challenging, but I don't think it is as dangerous as the higher mountain routes in the West.
Finding a diet that agrees with you, for months on end. You don't sound like someone who would want to eat processed/packaged food for long.
You might find the walking monotonous compared to running races. In a similar way, you might find it challenging to match your daily goals with your hiking partner's (I hike solo much for that reason).
Bugs. Snakes and bears might seem dangerous; bugs can make you crazy if you are bothered by them, or aren't used to living with them. Repellent and bug nets work. Be prepared.
I would take a few test trips to tweak your gear. You already understand the clothing and metabolism issues, but you might want to test your sleep system and pack fit/comfort. You can test packs just walking locally with a realistic load. Sleep systems vary in comfort (hard ground) and temperature tolerance. Sleeping well will help everything.
Speaking of packs, as a runner, you may be light in the arms and shoulders. Getting a good fit will help your comfort, assuming you aren't used to carrying loads and what I assume will be the biggest physical challenge for you. You have the legs/heart/lungs for the trip. Perhaps some good upper body strength building exercises? This will get you over the hump of the first few weeks– you will be conditioned after that no matter what :)
You can tweak gear as you go. There will be outfitters along the way and you will find what works for you.
You're in the right place. You can also find blogs on line from people who have done thru-hikes to get more info and a feel for the ebb and flow of traveling with someone for months on end.
It may just be your first thru-hike. There are more :)
Have FUN. We live on an amazing planet. Living in nature and traveling through it under your own power is the best way to experience it.