Maybe, but maybe not. Older pages may still get tossed out.
Unless you have buffer pool > total size of all DBs in use, you can't assume that there will be no page evictions. Also, data cache is not the only cache in the buffer pool, there are quite a few others, and then there's workspace memory needed for queries, etc
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability