Hi Anjan,
The general flow is that through replication you transform the data and move to a staging area and from where you move it to OLAP.
There are always options, replication is an option you can consider, but performance of data retrieval, query execution and ease of maintainence are factors that are better in OLAP systems than in non-OLAP system. The OLAP engine will have better performance when compared to replication in other datawarehouse.
Regards,
Kalyan.