IT industry structure cannot be created in a week. First they may snare low level job's like support, call centre's etc.,. Then they may jump up in the value chain and grab jobs of our programmer's. But that will take atleast 10-15 years.
in usa, a regular employee can get laid off anytime for any reason?
In certain jurisdictions I am familiar with (Europe, USA), an offer letter does not constitute a legally binding document. Resigning from your old job on the basis of one would be very risky, so it generally isn't done. Only once you have a contract signed by the company would you resign.
Is 19 years without a clearence job a problem?