Well I can confirm that Geoff Steel are definitely trying to continue next year with the NGTC-turbo BMW as they are currently advertising for a driver in a recent issue of Autosport. So (assuming they do find a driver), at least we have some confirmation of at least one BMW.
WSR are unlikely to follow Arena to WTCC, they have struggled to find the funds to run before - though they clearly would like to, seeing as several WSR engineers helped out Wiechers.
I think the real question is whether WSR run BMWs again - there have been rumours of MG returning and WSR have obvious links to that. If they get new cars, they will be NGTC I reckon (I doubt they will run S2000 cars like the '10 Focus or the '11 "World Focus") otherwise they will run the BMWs. There's little point in spending money and time trying to make a different S2000 car work when they are going to be phased out at the end of 2012.
For this reason, I doubt we will see many of the midfield teams like WSR, tech-Speed, Eurotech (already confirmed anyway), etc running anything other than NGTC. The difficulty is finding the funds to develop a NGTC when you have to tell the sponsors not to expect real results until at least mid-way through the year.
On a related note, the current cars up for sale that I've seen are:
3 Motorbase (Mat Jackson, Liam Griffin, Michael Caine/James Thompson) Ford Focus.
1 Central Racing (Lea Wood) Honda Integra
1 ES Racing (Chris James) Chevrolet Lacetti
2 888 (James Nash, various) Vauxhall Vectras
1 Geoff Steel (Dave Newsham/Tony Gilham) BMW 320si
So there are plenty of S2000 (and the BTC-T Integra) cars being sold. I hope Lea Wood is upgrading to something reasonably decent such as the 2010 Focus or the 2011 Civic (if possible).
I also hope tech-Speed manage to keep going despite sinking so much money into those 2010 Cruzes this year.