Turbine PIC isn't a requirement at several of the "major" airlines. At some however, especially desireable ones such as UPS or Southwest, it is. Continental, Northwest, and apparently atleast Delta don't require it. Is it possible to get the job without having the TPIC? yes, normally you'll need some inteneral recomendations however, but it is possible. Without that turbine PIC, and without a recomendation you'll be behind all the other candidates who have your same qualifications, and pilot in command time of a turbine powered airplane.
If you're trying for netjets (which i wouldn't mind myself) you can feel free to apply with 2500 hrs, if they give you the interview....you're set, if not, you'll be hanging out at the regional you're at until they do, which, might be after they award you with an upgrade. Another thought, were u just planning on getting your Multi-ATP in a light twin? It's nice to have the company pay for a certificate for you as opposed to you doing it all yourself as with the past.