I too have some industry insider info regarding the purchase of McIntosh- it was primarily a play for car audio and especially focusing on noise reduction in vehicles to eliminate most ambient engine or road noise. Bose engineered an electromagnetic car suspension system and sold it off a few years ago to an active suspension company, so they are always thinking about that sector. I think we might expect to see an expansion of the Mc name for OEM auto head unit partnerships (beyond Wagoneer), since the Bose name in car audio has taken a hit in recent years. But I do not expect any major changes in core Mc home audio equipment EXCEPT an infusion of cash that should positively impact engineering of Mc home audio.
I surmise that the SF purchase was due to a cash-flush company that saw higher than normal gross margins, just like Bose, and a premium speaker company that might somehow improve Bose's portfolio and perception with high end audiophiles. They cannot say that for their own brand.
I agree with many of the posters that Bose does not need to dismantle or negatively impact either company - the strategy does not appear to be a race to the bottom for parts or quality savings. You may not be aware that Bose is owned by Massachusetts Institute of Technology - donated entirely by Amar Bose upon his death. MIT's endowment fund exceeds $23.5 Billion.