I think it will actually be very good for SN; the RJ85/100 isn't the most attractive acft to a business traveller and hopefully LH's involvement will give them access to larger aircraft.
Also, BRU has an obvious attraction as a major hub, which - to its ultimate cost - (the original) SN never capitalised on. I think this will be very good for Belgium.
Ironic, though, that the descendants of Swissair and Sabena end up under the same umbrella!
As to where LH's shopping spree will end, hard to say? Austrian and bmi will probably be next.