Is Nickel eventually-consistent or realtime? How is it positioned: as a analogous to views were we expect a certain performance or as a common/primary feature such as reading and writing documents?
N1QL uses and depends on the underlying indexes. Today, that is view indexes, and the default mode is stale=update_after (eventually consistent).
In terms of positioning, N1QL will be the query language interface to Couchbase. The memcached and client SDK APIs for key-value access will remain the primary interfaces for key-value operations. View indexes will remain the primary mechanism for map-reduce and hierarchical aggregation. N1QL will be the query interface for ad-hoc queries, secondary key access, joins, transformation, etc.