So I recently found out that some danish dialects have gone through this lovely set of changes:
iː yː uː > iˀ yˀ uˀ (the developement of "stød") More vowels than just these and in almost all dialects including standard Danish. Occured via a pitch accent system, had a rather complex conditioning environment, sometimes incuded short vowels and only in Old Danish monosyllables + certain loanwords.
iˀ yˀ uˀ > ikʲ(ə) ykʲ(ə) ukʷ(ə) ("klusilspringet") in the dark green areas of this map http://jyskordbog.dk/ordbog/scripts/atl ... cgi?nr=2_1
. In other dialects ix(ə) yx(ə) ux(ə) or itʲ(ə) ytʲ(ə) uk(ə), sometimes with a conditioning environment of _# or _[#s]. Some dialects (Vest-hardsyssel and Fanø) also eˀ oˀ > ejkʲ(ə) owkʷ(ə) ((or maybe ejg̥ʲ(ə) owg̥ʷ(ə), source is unclear) (øˀ > øjkʲ(ə) only sporadically)
ikʲ(ə) ykʲ(ə) ukʷ(ə) > iː yː uː Quite recent and not in all dialects. EDIT: in some dialects to iˀ yˀ uˀ.
How realistic do you think it would be to have the first change occur in more environments and also in polysyllabic words but only on long vowels and have the third change not occur at all? What if the vowel system is still big but less crazy than the Danish one?