This is quite possible given the fact that Lumia 638 is the China Mobile variant of Lumia 635 with appropriate TDD-LTE bands suitable for India. It has support for Band 40, which is the prevalent LTE band used by operators in India as of now.
LTE network band: 3, 7, 38, 39, 40, 41
You would be happy to know that Lumia 638 comes with 1 GB of RAM and hence is an upgrade over Lumia 635 in itself.
Chris Weber, Microsoft Devices Sales, Corporate Vice President had also hinted about affordable LTE Lumia coming to India and Lumia 638 fits nicely in the scheme of things.