Need upgrade direction for Scan Engine 5.1 on Win2003

I have a client running Scan Engine 5.1 on Win2003 servers.  They are passing files to be scanned to the Engine from an internally developed app via ICAP.  As Win2003 has left extended support, am looking for upgrade advice.  It appears Scan Engine 5.2 runs under Win2008R2 which would address the Windows support isue, but Scan Engine 5.2 appears to have left support as well. 

I see references to move to Protection Engine for Cloud...does this seem like the right direction and does it support ICAP?  Looking for a tactical solution which will not require coding changes to thier in-house app.

Thanks in advance.