Non-clustered indexes can be numerous in SQL Server 2008 I remember from my Sybase days that SQL Server tables could support up to 255 indexes. One clustered index and 254 non-clustered indexes.

Denny's SQL Secrets When Should You Create New SQL Server Indexes? Here's how to spot when new indexes are needed to improve performance. By Denny Cherry 04/11/2014 ...

Non-clustered Columnstore Indexes (NCC Index) are also getting some enhancements in SQL Server 2016. The most notable of these enhancements is the ability to be updated.