i guess you have to look at as fisrtly, how many yds wil mcnabb throw for? i'll use the last 3 years to project. in 2004 he threw for 3875 in 15 games, 2005 2500 in 6, 2006 2600 in 10. if you project what he would have thrown for had he made it through the last 2 years each year he would have thrown for over 4000 yds. let's assume that mcnabb stays healthy and throws for over 4000 yds.
basing this on past stats...
800 yds to TE's
800 yds to RB's
which leaves 2400 yds to go to wr's
so who get's those yds? who knows, but having hear what andy reid has said about reggie brown, i think they expect more of him this year and i think he will be taking the lion's share of those yards.