I have referred to that many times and so has Montblanc. The manufacture is at LeLocle and Villeret. Minerva's heritage continues through the movements that are produced and finished at the Villeret manufacture and to your question will last as the movements are always signed Minerva.
Personally as an owner of a Montblanc Villeret watch and soon an 1858 Tachymeter with a Minerva movement, I see this as a good combination of both brands. Most acquisitions of manufactures don't even see their names carry on anymore (think Lemania, Federique Piguet).
Minerva will last and so far (and I really hope they will continue!) Montblanc has honored and upheld the traditions of Minerva. 
Cheers
Robin