Looks like there are going to be changes for Tier 1 extensions as well. The Migration Advisory Committe(MAC) has already started a consultation.
Document is given in the following link:
http://www.ukba.homeoffice.gov.uk/sitec ... iew=Binary
Pasting the relevant snippet from the document below:
Only Tiers 1 and 2 of the PBS are in scope for this work. Our
recommended limit for Tier 1 will apply to the current Tier 1 general route
only, including dependants.
It will apply to inflows into and from within Tier 1 from both within and outside the UK. It will therefore include in-country
migrants switching into, and extending under, Tier 1. The Post-Study Work
Route (PSWR) is outside the scope of our recommended limit: the Home
Secretary has said that the Government will be reviewing other immigration
routes and bringing forward further proposals in due course. The investor and
entrepreneur routes under Tier 1 are also excluded.