I don't think a real tyre has a linear correlation between flatspots and heat. If you had a hard compound it might not wear away, but would still be generating similar friction, and therefore similar heat.
A discussion for another thread? Todd? Axus?
To the original poster - you still need to worry about it. The hot spots will generate less grip, and as such will be the place where the tyre locks in future, causing more wear/heat (even before the effect of the flatspot comes into play causing re-lockups more likely). Also, your braking distances WILL be longer (although not quite as markedly as in real life), so without locking up you can be faster.
The latest nKP patch doesn't have the FFB shaking. It was removed for beta-testing, and Kunos forgot to put it back in. Quite why it needs to be in if the beta testers preferred it without I don't know. Hopefully he'll make the effect tunable, or I'll be billing him for a new G25 every month.