The 'self-improver' route has been effectively replaced in UK - though I like your Darwinian analagy! Many, many (we are talking hundreds, currently) new pilots every year are recruited into jet airliner flight decks in UK with around 200 hours. The training they got in that 200 hours is the best adaptation of an outdated system that the FTOs can make, but it is still outdated and rather less well matched to its demands than it might be. The proponents of the MCL recognise this, and recognise the fact that, increasingly, airline pilots will be recruited directly from FTOs. In many larger airlines (though not in UK), those FTOs will be part of the company's own structure.
You mention the military; their training has evolved in much the same way as the MCL seeks to do. Less time is spent learning generic, light-aircraft handling techniques and far more on techniques and procedures appropriate to the operational tasks the student will be asked to carry out. As an airline captain, I have little interest in how well the guy in my RHS can fly a Seneca or C152. I want to know that he knows the Airbus!
The MCL is, as I've said earlier, a work in progress. There appears (I'm not involved other than as an interested observer) to be a great deal of work going on to ensure that the final product meets the needs of the airlines that choose to use it. The indications are, incidentally, that it will be costlier than the current training system. There are many disagreements about how the MCL should be shaped, but there is general agreement that the old system is no longer appropriate in the more formalised and direct process of going from wannabe to 737 copilot.
For those who wish to, or whose national industry demands it, the old system will apparently remain available. the MCL would clearly be inappropriate for someone who intends to fly air taxis, or do bush flying, crop spraying or any one of the myriad of non-airline ways of earning a living in an aeroplane.