Yes, alive device will be fully functional as before. With one differemce: it will be in OpenMode (no write acccess to CAL ?: no device lock code possible! But even for that there is a solution) as flashing an OpenMode (ubiboot) kernel will bring the device to that stage. No return (other than full reflash).
To bring your alive device back to normal just flash the FW image with option --flash-only=kernel.