Why would BMW need to buy Lancia just for the brand name? They already own Triumph (left over from the Rover purchase)...they could just as easily revive that brand without the baggage that would come with Lancia.
Honda and BMW would make a perfect combination. Honda doesn't have RWD (aside from the S2000 and NSX) and BMW doesn't have FWD (aside from the Mini, which needs a new engine supplier). BMW would remain positioned above Honda's upper models creating (in the US), Honda-Acura-BMW (since Mini is just a niche product) heirarchy. It's a match made in heaven. All they need is a light-truck producer and they'd be unstoppable.