Nothing can stop Leverkusen to win Bundesliga this year and I will keep this bold prediction for the rest of the season. Sure , Bayern looks strong , healthy and always ready to win but Leverkusen looks more like a team than Bayern in my opinion and this will be a huge advantage when they will face each other later.
Also , Stuttgart really wants to catch an European spot for next year and by the way they are playing right now , they can achieve at least a Conference League spot.
You can't be very certain at this point in time because the point difference between Bayern Munich and Bayern Leverkusen will require the loos of one match by the later and the win of a match by the first and you will see a displacement in position, this speculation you have made will be true if it turns out Leverkusen stays consistent enough to be ahead of Munich by a good point difference and probably Munich experience a downtime in performance to permit such els Leverkusen still have to work hard if they must win the league title by the end of the season.
Only advice I'll give to Bayern Leverkusen is to make additional signatures into the çlub during the January Transfer Window upcoming. Tjays so they can meet up with whatever standard Bayern Munich comes with. Bayern Munich have been Champions for too long. I do think its time for another club to take over this season. Shame on Borrussia Dortmund they're the Arsenal in German Bundesliga they literally bottled the league when they should have won.
The Champions League will be difficult to catch, they'll end up qualifying for the Europa League Competition. They will definitely do better than that only if seriousness follows through!
Currently I'm yet to see any lagging aspect of Leverkusen that will need a replacement but then if they proceed to strengthen their bench I think it will be in their best interest just should Incase certain uncertainties comes up they wouldn't be caught unaware, if they have got the financial capacity to strengthen the teams reserve I think it will be a good one so they stand prepared enough against their biggest rivals in the bundesliga.