The bottom line is Apple can't be dependent on a competitor (Google) for a critical service (mapping). They just can't.
Of course they can. Just like they're dependent on Google for video streaming. Just like they're dependent on Microsoft for document formatting support. Just like they're dependent on Facebook and Twitter for social networking. Just like they're dependent on Samsung for hardware production.
There is no harm in using the market leader. Apple make money on hardware. They don't make money on maps. They just want the best maps they can to sell more hardware.
And lets not forget here, this debacle has proven (beyond all doubt that might have existed before) that Apple IS dependent on Google for maps. Because Apple demonstrably cannot even get close on their own.
So yes, Google Maps is back in to stanch the bleeding from the major flesh wound that is the new Apple Maps, but Apple can't turn back now. They have to keep working Apple Maps until it is equivalent to - or better than - Google Maps. Yes, it is a big challenge. No, Apple can't avoid it.
They're going to have to. Now Google Maps is available and will take majority marketshare, why would businesses or engaged consumers make sure Apple Maps is up to date? It's going to fall even further behind, not improve.
Next step: Apple search.
Only if Apple are truly, truly stupid.