AnhatVatsal,
We have not shifted from NOW to NEST. We've just added another software in our offerings so that we can serve clients trading in commodities too. Those who wish to trade only in equity, FNO and CDS can continue using NOW.
However, those who wish to start trading in commodities too, would be migrated to NEST automatically once their commodities account is opened.
So, if you do not wish to open a commodities trading account, things will not at all change for you. You may continue to trade the way you are doing right now.