Once MCL floats you're invested in a separate entity for 100% of...

Once MCL floats you're invested in a separate entity for 100% of their profits, not 45%.

I believe the share price fluctuations of both QBL and MCL afterwards will depend on the valuation of MCL and the perceived efficiencies of both companies operating by themselves.

So yeah people could end up selling QBL shares if they perceive MCL to be a better investment, but same can be said for any stock. And who knows, QBL could have progressed with their bauxite business by then.

Being holders of QBL now will give preference shares in MCL, but again if MCL does not live up to expectations then those shares can also be sold down.