(Currently) It will cease to exist in 2014 - there will be no such thing as the IMC rating after that date.
You can still train to fly aircraft by sole reference to the instruments, and fly approaches, but you won't be able to get a rating or licence endorsement by which you can use the training except for the IR.
Slopey, I'd have to disagree somewhat with your summary - although it may be true for many pilots, training and examination of IMC ratings could still continue. My understanding of the situation today (which BEagle points out above is still under negotation with EASA) is as follows:
The position today is that if you have a JAR licence (which is now officially an EASA PPL, even if it doesn't say so on the front), you can only add an IMC rating to it before 30 June 2012. If you have one on the licence by that time, you should be able to exercise its use until 2014. It's not agreed what happens after that but is extremely likely that the privileges will be continued (grandfathered) after that date. There is likely to be some benefit in getting this added/done before end June, because grandfather rights are expected to be continued in some form while new ratings after that date may be treated differently.
Since the CAA will start printing EASA licences on July 1st, I'd err on the side of caution and try to have any JAR-PPL licence change updated and issued by 30 June just in case the transition to the new system means that JAR-PPL licences can't be physically printed after that date. Perhaps I'm being overly pessimistic, but if I were running the transition I'd want to make it binary and not have old/new systems running in parallel for any length of time. It's sure to involve more than just printing the licences on different coloured paper
After 1st July, new IMC ratings can continue to be trained for and examined. I don't see why this couldn't be done in EASA aircraft. But they would be added only to a UK PPL licence - so if you had only an EASA licence you would have to be issued with a parallel UK only one. If you had both an EASA and an UK licence, you could exercise the IMC (in EASA or Annex II aircraft) until April 2014.
Thereafter, the IMC could only be used after 2014 on Annex II aircraft. Hopefully, something better will be agreed in the next couple of months.
Having spent a lot of time, money and effort to get an IMC rating myself before the deadline, I do hope it's been worthwhile.