Given the very expensive to operate F35 and comparably much cheaper operating costs of both the F16 and Gripen, I wouldn't be so sure about that, each type operating from their home base (Bagotville, Cold Lake, or wherever else) needs a cetain amount of support tied with that base anyway , 2 F35 Bases will inevitabely be much more expensive to run than 1 F35 base and 1 F16/Gripen base.
Over a certain number of fighters it does make sense to buy and operate a fleet of 2 types.
36 of each might be the absolute lowest limit but given the large discrepancy in flightcost per hour it might be worthwhile to consider.
Also don't forget that if they choose the F35/F16 option , they could still be tied on al levels with the USAF, who as things look now, will be operating a substantial amount of F16's and future derivatives for many years to come, just wait and see until january first when sequestration will hit reality.
It is already decided that there will be no massive layoff rounds in the US DoD and the 1.7% payrise will go ahead even if sequestration comes into effect.
The acquisition programs will be hit hardest and the F35 is going to see some massive cuts for both the USAF and US NAVY, that is pretty much a given ,1800 iso 2400 is not impossible, even further reductions are possible.
Just to set things clear, personally I think that a twin engined alternative to the F35 is still a much better option (SH or EF) but I don't think that the powers that be are willing to give up completely on their F35 dream, nightmare or not.