I have many dampened routes for now. What could possibly happen if I will disable BGP dampening that is previously enabled?
Prefixes get dampened because they are not stable; they are added and withdrawn multiple times. This is a sign of network instability. Having prefixes constantly added and withdrawn places a large burden on your routers, and it can cause lost traffic, broken TCP connections, etc. BGP dampening is protecting your network from the worst of this instability. What you need to do is determine the root cause of the network instability, and correct it.
It used to be (and still is with some companies) that if you have a lot of network instability, other ASes would basically cut you off and refuse to peer with you, or you would cut off and refuse to peer with other ASes exhibiting such instability, until such a time as the unstable AS proves it has corrected its problems.