The new service SIN-MUC-MAN is not confirmed. I haven't seen anything on the SQ-website. The booking systems still sends passengers from MUC via FRA to SIN.
There are just some paper scans of a press release on airliners.net. I do not accept this as official confirmation. It could be still a hoax.

If the new service will be commenced, we can safely assume that the SIN-FRA-JFK service will be switched to 77W (and not 388), after the 744 were retired. Otherwise they would be too much capacity between Germany and Singapore.