I've been in the business 40 years now. Started on AIX 3.2. Worked for Global Services half a dozen times. Every time, I've been 'replaced' either by H1-Bs or by 'changing directions.' The FTEs get RA'd, contractors get walked out the door. It never matters what contributions you've made, how well you fit, how many overtime hours you put in (80 a week for 8 months once). What matters is perception, image, and then only in Armonk.
IF you've never worked for IBM, DON'T APPLY!