I believe the announcements did mention mileage accrual to all Star alliance programs and with TG flight numbers it would appear it is simply a part of Thai and therefore star alliance. I guess it's just wait and see although my feeling is that Thai Smile will be part of the star alliance network. I don't think Thai would suddenly remove Star privileges on routes like Jakarta, Phnom Penh etc. Arrangement would probably be similar to regional operators flying for Lufthansa etc with LH flight numbers.