There are other species that can step in, but they aren't as easy to domesticate because they don't hive. Honey production is nil.

I just checked our orange tree in the back yard and there are bees all over it, one tree and about a dozen bees. That's not an indicator of the health of the bee industry -- as far as I know those are wild bees, not kept bees.

I checked the CA Dept of Food and Agriculture site and in response to the Euro Honey Bee problem they are considering using BumbleBees. There are options, we just need to explore them (not exploit them).