I think it is entirely unreasonable to conclude that Tiburon is "moving away from" Franchise after one cycle without major updates based on a one-game trend. We've gone through one-year lapses without major updates before - Madden NFL 11 comes to mind - and Franchise remains the most popular mode in the game. It's the game mode the core audience plays, it's still very important.
Up until this year, every Madden game since M12 has seen significant additions and changes to Franchise mode. It is perfectly reasonable to expect that to return to form next year, what with the two major tech pushes introduced in M18 - the transition from Ignite to Frostbite and the foundation for future Longshot iterations - in place.