Hi Gerrit;
Q: Is there a statement from SAP for the support of MS SQL Server 2014 and future versions in PB?
A: AFAIK all new development on PB at SAP has stopped. SAP is currently negotiating a contract with Appeon (as we speak) turning over all PB development to them. So as far as new development on SS is concerned, this will come under Appeon's control very soon. 
Regards ...Chris