I'm not seeing any advantage to having a dynamic MN collateral requirement.

I can tell you right now what will happen: the biggest holders will monoplise the MN 'allowance' and lock everyone else out.

Plus it adds code overhead to monitor and enforce the whole thing.

Just call it 1000SPR and have done with it, let market forces sort the rest out without things being weighted massively in favour of whoever holds the most SPR, which is all that a dynamic requirement is going to achieve.

A 1000SPR collateral would give a maximum theoretical number right now of 1500 MNs, which we know from DRK is not too many.

If decentralisation is the goal, implement some code to reject new MN's from certain IP ranges beyond a set % to prevent 75% of people just using Amazon, Vultr, OVH... or even better, come up with a way of allowing MNs to have dynamic IPs so people can run them on their home connections too.