The conclusion of this website is that the mainstream approach for nuclear fusion with Tokamaks and Deuterium-Tritium fuel will never lead to a commercial power plant. There are several reasons why this is the case and they are summarized below.

No fuel

Tritium fuel only occurs naturally in small amounts relative to that required for commercial fusion reactors. The "un-natural" tritium is produced by specific fission reactors which will most likely stop operating in a few decades. The existing reactor designs included internal generation of tritium but obtaining a net gain of tritium in the system seems very difficult or impossible. Even if this is possible, a significant amount of tritium will be needed for reactor start up and this will not exist.

Plasma loss due to disruptions

Plasma stability and disruptions have been problems for all magnetic fusion devices. Optimistically ITER will solve this problems but if it does not this approach to fusion reactors may stop there.