I understand the OP's concern about the challenge he has set. 99% of the backpacking community would not even consider a through hike of the AT. According to this forum, I believe only 10% of those that take the first step finish their goal because of physical, financial, or mental challenges. 100 % of section hikers that take the first step accomplish their goal because they can quit whenever/where ever they are.

To set such a lofty goal is admirable. That provides motivation to acquire the skills needed to succeed. Therefore I will be a section hiker next year and if enough sections are pieced together it will be mean I am a thru hiker. If not I will return when I gather more skills.