Nuclear, slow as it may be to build, is still the fastest option to actually eliminate fossil fuel usage. The other plans involving intermittent sources require immense amounts of energy storage. To put this in perspective, the US consumes ~5TWh of electricity during nighttime. The entire world only produces 300GWh of lithium ion batteries annually [1]. This is expected to increase to 1TWh by 2023 and probably 2TWh by 2030. But still, if we're talking about eliminating fossil fuel usage globally it'd take the better party of a century to build the energy storage required. Other plants for energy storage are either geographically limited (hydroelectric), or have yet to be built at any meaningful scale and have questionable efficiencies (Sabatier process, hydrogen).

France's nuclearization program took 20 years [2], but that's a hare's pace compared to building the energy storage required for intermittent sources.

1. https://cleantechnica.com/2019/04/14/global-lithium-ion-batt...

2. https://en.wikipedia.org/wiki/Nuclear_power_in_France#Messme...