I would not worry about Jet becoming a low cost carrier.

This was the announcement for starting JetKonnect:

http://www.jetairways.com/Cultures/e...ys_Konnect.htm

and this is one from a few days ago adding some more routes:
http://www.jetairways.com/Cultures/e...ys_Konnect.htm

The routes covered by JetKonnect are short sectors where there is hardly any premium demand and service is not required on sub 1 hr flights.

It makes sense to only have full service on sectors serving large metro cities where there is demand for both business class and full service.

BTW, Kingfisher is going along a similar route by introducing Kingfisher Red onto many smaller secondary sectors and restricting full service to between Metrocities.