MPEG4 exchange offer is not limited to South India customers. Exchange is happening all over India. They are replacing it for free only for those who have Kannada, Malayalam, Tamil or Telugu add on packs.
If you are in Delhi and if you have any of the regional packs mentioned above, you will also get your MPEG2 box replaced with MPEG4 box for free.
If you don't want to wait for free upgrade, you can upgrade anytime by paying certain amount. Or add one of the above regional packs and get it replaced for free