Why? at the moment there are two options - keep hunting for a CR, or spend 0.6cpp on P+P. Now there will be 3 options, with the mid-tier offering a very mild positive return on point value for J at least, unless you're acquiring at 1.5cpp or higher.
The only logical outcome is some of the demand from CR that wouldn't buy in at 0.6cpp will do so at 1.5cpp, and you'll have less demand for CR. Is there a reasoned argument as to why that would not be the case (other than speculation that QF will reduce the number of CR seats, which is a fairly pointless debate, they could do that at any time with or without this tier and you'd still be worse off).
The only argument I could imagine would be one of yield management, but QF didn't have to make any way for the 0.6cpp P+P inventory, so what makes us think that the 1cpp inventory would be much different? Yes, for some premium seats at 1.5cpp they might need to negotiate between CR, CR+ and full revenue but again, no proof that this reduces the number of CR seats, it's not that different to sale fares, there will just be buckets of availability to suit QF's revenue targets, which they've already signalled a hit to in order to accommodate this new tier. And let's not forget the revenue earned in selling the points in the first instance as well as the liability relief in burning them, so it's not just revenue per seat as a single metric that they're going to be tracking.