What seems likely at this point is that the Ernestine Wettins will eventually dwindle to one single surviving branch: the Saxe-Coburgs are the only Ernestine branch that show some promise of lasting into the next generation or so. The territorial divisions within the Ernestine Wettins were never understood to be permanent, and when one line became extinct the family as a whole would have to agree on a new territorial division between the surviving branches - but always whilst maintaining succession (to both lands and titles) within the male line only. The last such occurrence was in 1826, when the extinction of the Saxe-Gotha und Altenburg line necessitated a fresh division of territories by agreement between the surviving lines, under the arbitration of the King of Saxony as head of the Albertine branch.
We may then see the royal, grand ducal, and ducal Saxon/Thuringian heritages merged!
This is what makes Prince Michael's current position rather delicate: he and the heads of the other surviving Ernestine lines objected to the late Margrave of Meissen's dynastic innovations because they violated prior usage, and because they failed to obtain the consent of the House of Wettin at large. But now, facing the imminent extinction of his own line, he is apparently trying to designate his own daughter as his dynastic successor, replicating the same solution that he declined to accept for the Albertine branch. I would be surprised if this "solution" garners much sympathy or acceptance from the princes of the Saxe-Meiningen or Saxe-Coburg lines.
My understanding is that his daughter, Princess Leonie, is heiress only to whatever properties and fortune the family has and to any cultural positions the family exercises... minus becoming titular Grand Duchess of Saxony.
Regarding the Albertine Wettins: can we really even say that the Saxe-Gessaphes have "inherited" anything? The legal issue hinges, I gather, on whether the late Margrave of Meissen actually changed the house laws regarding dynastic equality, or whether he simply declared his nephew to be his dynastic heir by fiat. Everything I've read on the issue up to this point suggests that he followed the latter course.
Those who enjoy proximity to these descendants of the Saxon royal house seem to think the Margrave had the final work on the matter, ignoring that the last monarchical constitution settled the succession on the entire "Saxon princely house" (House of Wettin) at large.