Effects of Switching from Revitalash to Latisse

You won't have any negative effects. Both products work the same way by prolonging the growth cycle of the lashes. If you stop using any lash promoting product, your lashes will simply revert to their usual growth cycle and eventually their pre-treatment length and density.
Latisse has the advantage of being approved by the FDA and has studies behind it actually measuring growth and density.

When making the switch from Revitalash to Latisse, the effects should only be positive. Your eyelashes will not fall out. In fact, they'll very likely get longer, thicker, and fuller, as Latisse truly contains the active ingredients that cause the effects the other products often claim to.
Latisse, or bimatoprost, is applied to the base of the upper eyelashes on a nightly basis. There are potential side effects, so be sure to see a physician with experience for your prescription. You will likely begin to see the results in 4-6 weeks.