TCAS warning calcu.??

[MetoPower]

As the TCAS warning is given in accordance to a time to impact, and that you have them flying at the same flight level, the smaller the angle of convergence, the longer it would take.
And as you start with 900 Nm (this would be left or right, and ... say ½ a degree angle convergence), they could eventually run short of fuel before anything else....(according to type and fuel in tanks of course)

MP