Hi Bill,
I'm sorry if I dash your dreams... but all that glitters is not gold 
First of all, you have to keep in mind that SAP HANA is version 1.0 only... that means HANA alone is at the very beginning... in contrast the latest SAP BW Version w/o HANA is 7.31
That means there have been many, many years of development to come to this mature product...
With SAP BW 7.40 you get the full package of OLAP and HANA, which means the data warehouse is very up-to-date!
Second, there are many companies which store so much data in their BW that they have to archive e.g. 50% of it, before being able to get migration (to BW on HANA) done in a reasonable timeframe, plus for being able to make the licence costs, at all. You must not forget the ROI of it!
Usually, nearline archives are also column-oriented (like in HANA), so in general you could achieve some performance gain, IF you work with historic view. For current view, where information is stored in attributes (similar to star schema) then you encounter performance problems, which I cannot tell you yet, if completely solved under BW on HANA.
Third, purely from reporting perspective, you won't have benefits with BW on HANA, since the "old" BIA Technology was already in-memory... it just will become obsolete so that SAP is able to earn more money with HANA licences.
The most significant gain with BW on HANA is only from Backend (ETL) perspective, where many steps are executed directly on the database without the transfer between DB and appl. server.
I hope those first Impression (and personal opinion) helps a bit.
BR, Martin