Just be transparent about it, NJPW
whoever wins BOSJ can be rewarded by going to the other division because apparently no one wants to rebuild the junior division.
Except that's not what's happening? O'Reilly didn't make the finals. KUSHIDA had talked about trading in a prospective BoSJ win for G1 entry, just like Milano did in 2007, specifically because he wanted to represent the Jr. division against the heavyweights - that won't happen now, but the only one talking about changing divisions is O'Reilly apparently, which may have more to do with ROH wanting him in their title picture than anything, as New Japan are supposedly being quite picky about which ROH talents they want to feature as heavyweights.
As for the BOSJ, in my estimation Taguchi will likely defeat Ospreay and challenge KUSHIDA at DOMINION. Taguchi ended KUSHIDA's last Jr. title reign in 2014 and KUSHIDA's win over Taguchi in this year's tournament was the first time he'd managed to defeat him, so it'd be quite a fitting match-up.