Does the tax software include the medical expense deduction threshold of 7.5% for 2017?

It will but probably not until sometime late January due to the late change. 

Is is certain that the Medical Deduction Threshold for 2017 (for everyone) is 7.5% of AGI?

Yes.  But it will take several weeks or so for the software to update for the change.

Okay, because I ran an update this morning, and it still appears to be a 10% calculation.

That's because the IRS has not approved Schedule A.

Thanks for the prompt replies...