It's better for BMW to keep up with the new market and survive than to be stubborn about RWD and get into serious financial trouble.
BMW is premium luxury brand, they'd be more exclusive and prestigious if they only had 6/7 series but majority of us wouldn't have a BMW then.
Brands like Maserati and Jaguars, luxury brands with limited lineup have higher chance of failing and it's true; look at their history vs BMW.
I don't give a crap about Audi. That's a brand that started in the 90s.
But I respect and like Mercedes and they have FWD, A and B class.
As long as they still make pure-sex fun RWF roadsters, I guess which would be renamed Z3, it's cool.
We won't know for sure, but currently, BMW's plans with roadsters according to Scott26:
Z1: compact FWD, expand buyers and share cost with Mini. Smart business.(?) ~160inches length
Z3: this is the new (unconfirmed) name for the previously rumored Z2. It will be a soft-top. Market competitor to Mercedes SLK and Audi TT. ~165inches.
Z5: up-marketed/successor to current Z4. It will have hardtop and it will be more of a gran turismo than a pure roadster/sportscar (that's the current reputation of the Z4)
I'm not sure who this car would compete against.. I guess the SL? But I doubt it will be as big or as expensive as the SL