It has not been said that it will be extended, it has been a sucess and Im sure the the dealers will push for it but I think personally that it won't was it has been running for quite some time now and has already been extended. It is only 1/3 into the year, hardly what I would call late into the year.
If you are buying a new car purely to have it from day one in the year and the new reg it brings then wait, but there is great value out there now from what I have seen and as I said you will get your value out of the car both this year and for many to come if you can afford it.