Will Java 8 create a new List after using Stream "filter" and "collect"?

If you actually want to modify the original list, consider using removeIf:

list.removeIf(i -> i < 2);

According to the Javadoc, passing the Collector returned by Collectors.toList() into the collect method will create a new list.

public static <T> Collector<T,?,List<T>> toList()

Returns a Collector that accumulates the input elements into a new List. There are no guarantees on the type, mutability, serializability, or thread-safety of the List returned; if more control over the returned List is required, use toCollection(Supplier).

The original list remains unaffected.