I would believe it will. It may break your current setup on Verizon Prepaid and no longer allow you to use it on that network without a reflash...that's if the flashing method is the same on ICS than it was on GB. Personally, I would sit tight and keep what you have setup. Calkulin 3.0 is great and you are not missing anything by not taking the leap to ICS.
If you know for a fact that other people in your situation have taken the OTA update to ICS without ill effects then do it...until then, just keep the status quo until there is a sure method to update and keep your network.