There are three O line configurations that I could see the Bills moving to (assuming they sign Incognito and everybody else gets healthy).
Situation 1:
LT - FA/Draft Pick
LG - Levitre
C - Wood
RG - Incognito
RT - Butler
Wood is moved over to his college position, Levitre can continue to grow into as a guard, and Incognito brings the nasty. We get some depth as Hangman would be moving to C, G backup. The questions would be 'Can Butler stay healthy?' 'What are we getting to address the LT position?'
Situation 2:
LT - FA/Draft Pick
LG - Levitre
C - Hangman
RG - Wood
RT - Butler
This situation would be about maintaining stability in the middle of the line and building out from there. Incognito would be coming off the bench as a backup. Still have the question marks with Butler and at LT.
Situation 3:
LT - FA/Draft Pick
LG - Incognito
C - Hangman
RG - Wood
RT - Levitre
We could still maintain some consistency in the center of the line with wood, hangman, and incognito. Levitre got some reps at T this year and didn't seem like he was overmatched. An offseason of reps will do wonders for Levitre as during the season he just stepped in and was solid. We would be removing having to rely on Butler and allow him to come off the bench (less of a chance for him to get hurt) where he now has experience to play G, T. The question would remain about the LT position but we'd be down to one.