If the UKBA make any changes (again) in line with the one you suggest, then they will publish a date AFTER which the new rules apply.
All applicants will need to fully comply.
I've read that the UKBA were considering raising their pass level from A1 to B1. In your specific example your scores of 4 are actually already at level B1 for IELTS, so I wouldn't worry too much.
