How feasible is fusion power in the future and how is it going to be modelled.

I would say that cold nuclear fusion using the approach of critical mass as a catalyst is the most feasible. By placing Cm-246-96 in a light water nuclear reactor and removing the sample to measure whether any Bk-247-97 is made is the best test possible for cold nuclear fission. I think that the Sun makes U-238-92 with a 4.46 billion year half life, to complete proton-proton nuclear fusion by alpha particle decay.
The high temperature gas cooled nuclear reactor with a uranium oxide or thorium dioxide fuel blanket, is the best fission reactor of the future. Hafnium from nuclear waste also has a high melting point, and it can be electroplated on to fuel rods for cladding and it does fission as element 72. Plutonium or uranium fuel alloyed with beryllium-9-4 has the best moderator possible, as a fast neutron endothermically fissions beryllium to make two slower neutrons. To take a heat load perfectly, 2% plutonium-239-94 or less alloyed with beryllium would be clad with hafnium to maintain and improve current nuclear fission use.