I'm honestly not sure if there's any real way to implement it...
But I really, really liked the Geomancer PrC from 3.5e. It was absolute crap if you were playing a regular game, but amazing if you were doing gestalt. See, it required that you have both arcane and divine spellcasting...but it would only advance one track. This sucks, to put it mildly, since the Mystic Theurge PrC is a double-progression class with the same requirements...and it's generally regarded as Pretty Bad already.
But...since it wasn't a double-progression PrC, it was perfectly fine to progress it on "one side" while progressing the other spellcasting type on the other side (per the official gestalt rules...which a lot of tables ignored but still!) Its greatest feature was that it let you blend together the best characteristics of your casting traditions, other than which stat gave you bonus spells (though that had a workaround via an obscure feat): you could cast arcane spells up to [Geomancer level - 1] with no arcane spell failure chance, and you could choose which benefits applied to which spell pretty much however you wanted, basically erasing the distinction between "arcane" and "divine" magic. It also had a whole bunch of "Drifts", where you would get progressively more powerful inherent features, as your body took on the essence of the land through which the ley lines flow.
I played a really really cool character in a high-level (and then epic) 3.PF game where we used mostly PF rules with 3.5e content allowed if reviewed by the DM, where I put together an (IMO) really fun, thematic character built around this "all magic is magic" thing. Menhir Savant PF Druid archetype (all about ley lines) and Planar Shepherd on one "side"; Exploiter Wizard archetype (taking the Void school, which also does ley line/magic-bending stuff), Geomancer PrC, and Archmage PrC on the other "side". With the aforementioned feat workaround to make all aspects of my Druid spells key off of Intelligence, I had the world's nerdiest planar-astronomer druid, for whom both his magic and his body were malleable.
I know a 1:1 copy of this simply wouldn't work in 5e--it doesn't have ASF penalties, for starters!--but it would be really cool to see a "Geomancer" Wizard subclass that is to Druid what the Theurgy subclass is to Cleric: a little dabble of Druid-like flair and flavor, the ability to scribe Druid spells (assuming you can find any!), and then your subclass features can start out as Ley Line benefits, and add Drifts as you become more and more attuned with the land--less "wild shape" and more "wild attunement."