People would be for BS, if BS would have alternate things to do (PVM in twink range) and if it would not end up running 5 minutes from spot to spot. Lvl 30 and 60 and 100 BS are tooo big. We know this since years. Even if there are 8 people at one time, finding somone to fight is just to slow and damn boring. I remember, back in 2009, we managed to run BS 100 with lots of twinks, like 12-15 people, and still it felt empty. Even this lvl range is most balanced in all ways, it wont run because 1) no PVM content 2) its boring like hell.
Your idea is not good at all.
FC could provide an APF for lvl 100 and it would be good. Let it be simple APF in APF area (mission) like Coocons, but with general at end and some minor additional loot. Simple to introduce. Could boost up this lvl range. I still keep 4 twinks geared