Is Lewis for sure leaving? If he doesn't, the Ravens would surely do exactly what the Broncos (and the Ravens) did last year and have Lewis get most of the carries and Anderson less. Anderson right now just took the place of Chester Taylor.
I can't imagine they'd go into the year using a 32 year old RB as the sole carrier of the ball, would they?
I suppose if they go after a RB in the draft and drop Lewis, then he would probably get some play time immediately. Good luck there.