Harper extended the 6% by 3 years.

One of the reasons the provinces refused the offer was because the flat 3.5% offered by Trudeau/Moreau to the provinces was less than the formula (nominal GDP growth with a floor of 3%) proposed by Harper in the long run.

In the end the provinces that signed side deals with the feds got the added mental health funding while maintaining the Harper Formula with an opening for a better deal in the future for the time being which may or may not be the smart thing to do and only time will tell (getting the money now is smart, allowing the feds to dictate how it is spent is not).