I would take whatever CTC tell you in a presentation designed with the explicit intent to sell a course to you with a very large pinch of salt; it's of course in their interest to paint a rosy picture which may not correlate to reality.
Also there is no evidence that MPL scheme airlines are taking the minimum number of pilots they need as you put it, for all we know they could be taking on vastly more pilots than they currently need with a view to job creation in the future.
It seems more likely that these schemes will increase in number and capacity - and let's face it CTC will not be bothered whether pilots join airlines through the hold pool or through the schemes they run as they get paid either way.