Chris - PSLs could face a real risk of going under in certain parts of the country if rents were capped at 40% of MW. This comes back to the model of supply and demand I have shown you previously - suppliers will supply more when the rent is high, less when the rent is low. If you are calling for rents to fall, you are also calling for supply of homes to fall as well. Some suppliers will be able to adapt. Those that can't will, like any private business unable to make a profit, go under eventually.
You seem to have this conception that social housing can afford to provide lower cost homes than PSLs. Have you asked yourself why this is possible? The answer is subsidy. I have called consistently for all forms of subsidy to be withdrawn - this means subsidisation of social housing providers and other businesses/organisations, and also subsidisation of individuals. This also means minimisation of taxation. My proposal would help people on low incomes as, when you take into account tax on consumption etc, they are paying a disproportionate amount of tax.
I would be genuinely interested to see how the proposals you are making are affordable, and how they will be put into effect without harming the individual rights of property owners, without leading to reduced supply of housing, and without resulting in reduced employment. Clearly I think you will not be able to. But I am prepared to stand corrected.