Someone just recently began a petition through change.org (a useful little site!) to add bots to MW3 just like Black Ops had. If nothing else they can be patched into MW3 local play in the same manner that they were patched in for blops.
People can also send tweets to @fourzerotwo, @GlenSchofield, and @MichaelCondrey requesting the return of this feature. If you don't have a twitter account it is actually quite quick & easy to set up.
Modern Warfare 3 isn't yet the game we thought it would be, so make your voice heard if you want bots back! Go ahead and start your own threads discussing offline bot support and your reasons for wanting it, and spread around the petition and tweeting.