I think a slight improvement over this model is to have a forward-looking CTO/Lead Developer/etc. who incorporates new technologies into the overall plan with s

I think a slight improvement over this model is to have a forward-looking CTO/Lead Developer/etc. who incorporates new technologies into the overall plan with sane fail states. This allows the overall technology stack to remain fresh, the developers to stay motivated and current, manages the overall amount of legacy code, while also managing incurred risk effectively. It can also lead to company investment in those new technologies, i.e. training time/budget or conference tickets (depending on what's relevant). Tl;dr: put your magpies on the top!