First mind that not everything BMW are testing automaticly means it will be produced ...

Yes, BMW are testing targa solutions for their future models. They are testing it on a current Z4 coupe & will do the same with upcoming 2er variant ("coupe-targa"). All in manner to make the cars more attractive to American buyers - who are more keen on roadsters & cabrios, and large fixed or retractable glass roofs. So targa-coupes will be a bit more attractive than regular metal-top coupes.

Right now they are still testing the possible solutions - mind that also 3er cabrio was tested with a sunroof, and also with canvas folding roof, yet both solutions did not come into production - and I have no info on marketing schedules for targa models (it is even possible that only Mk2 Z4 coupe will get such roof). It depends when the solution will be production ready. Stiffness, weight, head space - all the issues that have to be addressed before production.

But as said - there is an intention to offer targa roof on a Z4 coupe variant & on one of the 2er variants.