Hi Lee,
the point is what you're using BW for.
If your primary use of BW was just as a operational report repository for your SAP applications (ERP, CRM, SRM, APO etc.), then you're right, BW is not needed anymore, since with native HANA Live delivering real time operation reports on top of the transactional data, that's a much better design.
However, if you're really talking about your enterprise-wide data warehouse strategy, where you might have data coming from several sources and where you're going to maintain your corporate historic data for legal & financial reports for longs period of time, then yes, BW (even more, HANA BW) is the way to go.
Best,
Henrique.