As a mostly fortress playing dwarf overlord I STRONGLY suggest playing adventure mode a few times. It gives you a much better understanding of the combat mechanics and just how deadly certain things are. It also gives you a better understanding of dwarven sleep/eat/drink needs as well as training certain skills. I learnt a lot about the best way to train wrestling dwarfs by being one myself.
BUT most importantly it will give you a better understanding of the game as a whole. The view you have that your "game" style would be marginalized is flawed even if no further changes were made to fortress mode. With the ability to retire fortresses you can now focus on building an ENTIRE civilization with multiple fortresses and heroes and carve your own path through the world. Exploring the world, seeing what is there and learning the history of it and the various creatures/races who live there is the REAL game. It just happens that fortress mode and adventure mode are the most fun ways to do this! Any changes toady makes to the overall world/adventure mode will always mean new fun and exciting interactions in your fortress.
I expect my first world in the new version (presuming there aren't any super game breaking bugs) will have multiple concurrent fortresses as well as several adventurers. I plan to do things like retire a fort and have my hero come deal with forgotten beasts and be rewarded with new gem encrusted Armour or a donkey bone encrusted crutch when he loses a leg in battle.
By limiting yourself to only playing one fortress on each world you gen you miss out on a whole wealth of stuff which makes the game more interesting. You probably have no understanding for the layout of your continent or where the various civilizations are located and what their interactions are. All this stuff will be much more relevant with the new version. I derive so much more joy from killing elves once I realized their borders were encroaching into our dwarven kingdom and blocking expansion. Similarly I realized there is a huge kobold lair really near one of my embarks. Killing those guys in adventure mode would presumably reduce the number of annoying thefts in my fortress in the new version.
I see this new release as going from building a fortress to building a civilization and what could be more exciting than that?
I strongly recommend exporting your data in legends mode and using the excellent Legends viewer in conjunction with isoworld to see the bigger picture.