If these BSNL plans come in to effect from Feb. 1, 2012, the FUP limits are higher than the Airtel 4 Mbps plans. Then, I hope Airtel will also increase their limit of their existing plans to more than what BSNL is offering, say for example 200 GB for Turbo 150 (Rs. 2099/- plan). Otherwise, it might not be a bad idea to move to BSNL.
Offcourse, these are very good plans but the revised speeds and the revised FUP limits are only available in few selected circles.So, i think Airtel won't revise it's current tariff plans unless and until BSNL implements the revised version of these plans PAN India.