How long will VPN protection last?

The use of VPNs for private surfing and circumventing ISP shadyness is a hot topic and worksfor now.  My question is, how do these major VPN providers keep in the clear?   I use PIA (have been for a while) and many of the gateways are in the US.  How long before the ISPs start to identify the source of traffic from the servers of major VPN providers and start their bullshit from there?  

it shouldnt matter, the vpn use the same infrastructer, or level 1 ISP that's your ISP uses.