If i am working in as Blue-prism developer and if the tool is replaced with more robust tool and market booms with new tool will this be threat to my job?
Not necessarily. You'd need a crystal-ball to know really... but your employer is likely to consider your skills as a BP developer and your general ICT knowledge as valuable for whatever other RPA product they acquire. Also, is BP development your only ICT/development skill? because that's a bit strange... In the end, the name of the game for a developer is to recycle your knowledge continously even as you build it up. Actually, exposure to another RPA tool should be seen as an opportunity for you to learn/build up your skill-set, not as a threat surely...? Good luck not getting chewed up for asking non-technical questions in here anyway ...