If hair loss is gonna make T not worth it for you then I recon you should be reading up (if you haven't already) on all the other potential side effects including shortening your life span before you think of going down that path. Transitioning isn't an easy option, actually it's often a last option.
The men on both sides of your family will tell you what to expect, the reason they used to think it was just on the mothers side is because the gene they linked balding to was on the Y chromosome, they have now found there is another gene that has an impact so both sides of the family are relevant. If you have a brother that'd be the best person to look at but all other males in your family will give a hint, understand tho that nothing is guaranteed.
It's something I recon we all think about at some point but seriously, if hair loss is a deal breaker then there are other things here that you need to look at.