Bex 3.x to 7.0

I am looking for information whether current SAP BW set up i.e. BW 7.0 with Bex version 3.5 is supported by
SAP in near term ? Kindly anyone tell until when 3.5 Bex is supported by SAP?

OR SAP recommending BEX  upgrade to match backend BW 7.0?

Thanks,

Angavai