If they block SSH tunnels for instance no sysadmin will be able to do their job. Same for VPN. A lot of people work remotely.
I will laugh my ass off if they try to do that.
At the same time I won't be able to access my VPS anymore :(
But you can tunnel encrypted data over anything that can carry a signal, and stuff IP datagrams inside it. This will only stop people that are "casually" looking for stuff and don't really care.
Latency might suck. But if the filters become a problem, you'll start seeing VPN applications with "UK filter modes" that use whatever the current simplest circumvention method is. Heck, I'm in the UK and I'd go into business selling VPN solutions like that myself if the filters get obnoxious enough for that (through suitable shell companies somewhere more favourable). The trouble with a business like that, of course, is that the market will be limited as long as the filters are not mandatory.
But just as an illustration of how ludicrously infeasible turning this into full censorship is: If they allow HTTP through at all, you could easily create a VPN were the packets are exchanged by ensuring every Xth character is lowercase for 0 and uppercase for 1, and serialise your packets by downloading / uploading hacker news comments to the VPN server, with the case changed. Or you could use a thesaurus on both ends, with an algorithm for assigning 0/1 to words, and rewrite the text by looking up the next word and deciding whether (and if so what) to rewrite it to.
Of course that'd also be ludicrously slow and waste tremendous amounts of bandwidth, but it's an example on the far extreme end. More likely if they ever try to make this mandatory and actively filter, it'd likely start out with just be a matter of changing port numbers. The next step up in escalation would likely be wrapping the data in something that looks like you're talking to a DNS or mail server or similarly slightly massaging the data.
It'd only be somewhat tricky if they get to the point of trying deep packet inspection and validating that the contents matches expectations from the protocol and doesn't look "too random" for every protocol people might use.
(As a last resort we'll just have to implement IP over Avian carriers: http://tools.ietf.org/html/rfc1149 )
Dirty, filthy sysadmins :)