It would depend on the new law essentially; if the ISP blocks access to the known VPN services, of course those VPN services won't work, but it would be difficult to pass a law like this
VPN services can be used for other security reasons and not just to circumvent blocked sites, and so implementing such a law could be asking for trouble
VPN services can be used for other security reasons and not just to circumvent blocked sites, and so implementing such a law could be asking for trouble