The question regarding the future of twin engine helos is actually interesting.
First, consider the fundamental reason for using twin engines. It is primarily because existing turboshaft engine designs were not perceived as having an acceptable level of reliability for the given applications. On the other hand, using a single larger turboshaft engine would give better fuel efficiency and much lower manufacturing cost.
The new generation of turboshaft engines are far more reliable than previous ones. So I think we'll see more new helo designs using a single engine instead of twin engines.