I honestly don't understand their strategy with Final Cut and Logic Pro. These apps can't make very much money, they are a suspiciously good value and they never upsell you on anything. Logic Pro cost like $300 over a decade ago, it still costs $300 today, and all major updates in that time have been free for existing users. Compare that to a competitor like Ableton Live which has cost like $800 since Ableton Suite 8 and major upgrades have come out every 3-5 years and cost a few hundred dollars to upgrade. Or compare it to Pro Tools which now costs $300 for 1 year of a subscription license.
So it really doesn't seem like funneling Garage Band users to Logic is a very high priority for Apple. More likely Garage Band and maybe even Logic Pro are loss leaders to show that the mac is a platform for creatives.
On a related note I never understood why they killed off Aperture which was beloved by many photographers, why didn't they keep a similar upgrade path from the free Photos app -> Aperture like they did for Garage Band -> Logic Pro? Seems like another indication that they really don't like to be in the pro software business, they are only there reluctantly at this point.