While browsing the Opel's EPC program (spare parts catalogue), I saw the new engine codes : A10XEP, A12XER and A14XER.
I don't know anybody here knows anything about this but I guess we can say it is official now, as EPC program is Opel's own information source.
Then I made a search through the Internet using those engine codes and found a GM document. There it looks like that A14XER will have a maximum power of 100 hp and a maximum torque of 130 Nm. Also the F13+ gearbox is likely to be replaced with the F17, the one used in the Astra H.
A13DTH engine code is also listed there and it looks like max power has upgraded to 95 hp and the torque to 210 Nm.
Also a new 1.4 turbo engine with the code A14NET was mentioned in the document and the max power is listed as 136 hp and the torque is 200 Nm. The gearbox is likely to be 6-speed M32, the one used in the GSI and OPC. But it is not yet clear whether this engine will be used in Corsa D or not.