It was very much used (abused?) by Russians since its inception, and was already in trouble for few years once the investment limits were raised. Although it was one of the most affordable and efficient in Europe, it was also less conducive to the eventual receipt of citizenship due to a long wait time (10 years) and language requirements (Latvian is one of more difficult ones in Europe). This decision should have come as no great surprise.
I doubt Portuguese will follow in their footsteps…