Bases.
About 20 years ago SIA had bases worldwide, pilots on those bases were contracted until 60 as was legislation at the time. Tipped out at 60 in the UK they sued for ageism (as the legislation was changing and you could legally fly to 65 pretty much worldwide but not with SIA) and - certainly in UK - won substantial damages. SIA were hamstrung by UK law which governed the base. All bases - LAX, ORD, SYD, AUK, LHR - were gone with 4 months of the judgement. Employment was still guaranteed but you had to uproot to live in SIN, accept a SIN contract and settle into the SIN roster.
I'm sure that Emirates management are well aware of these pitfalls with bases, local emloyment law etcetera and are unlikely to dip their toes in that water, especially if they're getting recruits through the door based Dubai.
S