be going to have to ... 近い将来しなければならない

You'll have to と You're going to

双方とも、未来のことについて。You'll have to ... が「将来 ... しなければならなくなる」、You're going to ... は「近い将来 ... しなければならなくなる」となる。

I'm going to have to replace my laptop.
My brother has one he wants to sell.
He does?
Yes. Do you want to talk to him?

How much would that cost?
（そうしたら）いくらかかりますか？
I can't afford that.
そんな余裕はない。