I put these in a different thread discussing twists to be Made now that the future of BT is open, but I think they could be tackled in FanFic fashion. As I have a lot on my plate, I don't know if/when I'll get around to any of them.
Trible 80 BatttleTech - Borderlands: Actually, with the rate that more and more people doing anything in the BT:U show signs of some form of mania or insanity, I foresee that at some point in the future of the BT:U, the last sane person will die of congestive heart failure, and every last person left in the Inner Sphere will be partly or wholly insane. Medical programs had long diagnosed this eventual outcome from extended hyperspace exposure and breeding, but the find was merely foot-noted and largely ignored. Someone did discover it, but after her mere comment of 'interesting', she started ranting lines from Shakespeare and continued plotting the destruction of her world.
Tribble 81 BattleTech - Under the Dome: It turns out that our portion of the galaxy is only about 2000 light years deep, and while there is a major push by the Explorer Corps to find the descendants of Kerensky, some expeditions take to the z-axis. They both discover a great barrier that stops all FTL travel to the farthest stars at the edge of the galactic arm. Commissioned to explore the barrier to its extent, the soon find that it is more like a large sphere. The true diameter of this bubble won't be fully realized until 3250, once data is finally compiled and some basic math applied, and other expeditions past clan space confirm it is complete.
Tribble 82 BattleTech - The Damned: First contact with aliens comes shortly near the end of the 32nd century. A small task force of mixed aliens comes across one of the periphery worlds, having taken a circuitous route to explore. They bring word of a giant galactic war between two ideals embodied in two mega-coalitions. It turns out that, as civilized species, they aren't that great at fighting, and were looking for a better race of fighters. (With an established series of star nations, I can see this going many different ways than did in A Call to Arms.) The other coalition, by pure accident, comes across the world of Ketatoa, after their disastrous set-backs by the new aggressive race, they see the small collection of similar peoples as a good starting point for an army of their own.
Tribble 83 BattleTech - Gateworlds: It turns out that Devlin did disappear from human occupied space. After assuming the control of Terra, extensive analysis of WoB research into a Belter-discovered phenomenon at the edge of the solar system prompted further investigation by Stone and his Republic. The phenomenon turned out to be a wormhole leading to an unidentified part of the galaxy, or another galaxy. Exact details aren't clear yet, even with computer assisted astroanalysis. One thing was certain, the next system had more of these tunnels. Further exploration finally revealed a race of sapient non-humans dominating all aspects of the 4th system in a chain leading to Earth. Years of covert surveilance gave the Republic leader an erronious confidence that led to a botched first contact. By the time he gets back to the Inner Sphere, and Earth, he contacts Levin and orders the Fortress - a technological defense against the wormholes and any unforeseen threats which might come through. The alien horde is blocked from Earth, and it is up to the Republic or its successor, to prepare for their coming.
Tribble 84 BattleTech - Atlantis: Atlantis is real, and it feels threatened by the blind expansion of the war-like stelar empires of their lost terran-born brethren. After eons of careful observation, the council of ten Kings finally holds a vote, and the pro-active prevention view takes the majority. They invade to protect their realms.
Tribble 85 The Auquarion: (Oceana?) is a water world, one of few, where the largest land mass is nothing more than a really large island, but there are many, many smaller ones. Most land holds are raided at the outset of the monsoon and hurricane seasons by small but well-equipped forces which are believed to be dissident pirates. They come in with the rains and quickly disappear, usually unable to be tracked. Oft' times, mercanaries are hired by provincial lords to defend various holdings. One lord has been paying attention, however, and has noted that the raids are not about capturing people or material. He has also been spending a large portion of his wealth on a special submarine carrier and fleet of submersible combat vessels to take after the raiders the next time they strike. With a select mercenary force which specializes in submarine and aquatic warfare hired as advisors, as well as technical aid from other off-planet concerns, he believes he is ready to start ridding his world of what amounts to a nest of rats.
It turns out the raiders are part of something much bigger, leaving some of the specialists wondering just how big, and if it is isolated to just (Oceana?).