I'm not going to get too excited about rumors of possible tests of something that may or may not reflect a final product.
But, in terms of my first choice for a final product, if they ever allow guests with advance reservations to also get some FPs same day (which I expect), I don't think that availability should be contingent on using your reserved FPs.
As you point out, this approach could create a demand for morning spots from guests who want to use up 3 FPs as soon as possible so they could get more. But, that strategy would run the risk of getting MORE FPs that would be less valuable in terms of the length of the lines skipped.
For example, if you choose FPs for the 3 mountains at 9-10,10-11, and 11-12 you could use those and then try to get a 4th FP as soon as you get through the last one. But, especially at a busy time, the selection of FPs might be limited, and you would have used up your 3 reserved ones at times when the standby lines would not have been that long.
I would prefer a system that would allow everyone with advanced reservations to get more for same day use, regardless of whether you have used the others. The availability of those extras could be controlled by things similar to the paper system, like no more than one every 2 hours.
It will be interesting to see how this develops.