The 0.6.0 release will include a new API called IValuedNode which centres around boosting SPARQL expression evaluation performance by making it possible to persist strongly typed values through the expression tree
While most node classes including some of the Virtual Node classes where already upgraded to take advantage of this feature it should also be added for virtual literal nodes. Rather than having a complex hierarchy of multiple virtual literal nodes the intended implementation is to add logic to BaseVirtualLiteralNode so that it implements IValuedNode and it materialises the strongly typed value on-demand as needed