Hello Sahil and Welcome to the Forums,
I think nearly profession under the sun is vulnerable. Keeping reinventing yourself is the key. If the news about mainframes affects you, please check this
google search on mainframe is dying (which gives you 2,11,000 results) and then see
this google search on JAVA is dying (which gives you 10,80,000 results) - does that mean JAVA is dying rather fast!? A stupid comparison derived from the number of results count we get but then the 'fear' you talked about should exist for all and not only for mainframes.
Mainframes is not "that fancy" (depends on one's mileage though) compared to the other jobs available in market such as the Jobs from Facebook or google (or I'd say in web-development, android or animation) but then that's a different league altogether. In 70's and until mid or late 80s' if you were in to IT you were working with Mainframes and most of the business was driven to them to make repeated tasks easy. Later, when PC became affordable, other IT jobs came to the market and they provided better money - people saw the shift in tastes for IT and
Mainframe was about to die, per market pandits. And then social media changed the market very differently and
Mainframe was about to die again...
I think now-a-days it has changed how the business was thought of compared to how it was done in earlier IT days - though how the IT worked still remains, pretty much, the same.
Just my $ .02...