Hello Anil,
why do you think that using SQL and window functions lead to sequential query execution?
I've now seen so many of this kind of questions here in SCN:
"Is there a CE-function for it?" always right after "How can I achieve xyz at all?".
CE-functions are not the be all end all of SAP HANA programming.
In the vast majority of cases I'd recommend to rather use SQL instead of CE-functions.
SQL is well known.
SQL is very productive and semantically rich.
Compared by the number of code lines per query, SQL wins hands down.
AND:
It is optimized very well.
It can be easily run in parallel.
It is not the second best choice in SAP HANA.
On top of it it provides much more features than the CE-functions.
Just like the window functions.
So, no, there are no CE-versions of the window functions and for the time being I'm not aware that there will be any.
What should be clear with window functions is that they aim at the result processing of queries.
And as usual "result" means: small, condensed, data sets, key figures,aggregated numbers...
It clearly doesn't mean: tons of raw unprocessed data that is supposed to be the answer to all questions. 
Ok, that got a bit long, but I felt that it really needs to be said at this point.
Happy weekend,
Lars