Definition from Wiktionary, the free dictionary
- It's not hypercorrection at all. Duden says the genitive is the standard and most common case with the preposition. (Quote: "bei Voranstellung mit Genitiv, seltener mit Dativ, veraltet mit Akkusativ" .) To me personally only the genitive sounds normal after entlang (and I'm not someone who uses much of a genitive in normal speech). Anyway, the most usual form is postposition + accusative. ---- There is indeed frequent hypercorrection with gemäß and some other prepositions, though.