Introduction:
There is a push for single type fuel which brings a host of other problems for land investors who invested under the premise that fuels will have fluctuating monetary values over time relative to each other. Land plots have been valued accordingly and plots that have a diverse set of fuel nodes and element resources were thus valued higher than nodes that only had 1 or 2 of the 3 fuel types/resources. A change to a single fuel economy would undermine these strategic investment decisions.
In the short-term, there could be an argument that this is best for the game in its current state, but I want to offer an idea to give a better use case for having 3 fuel types that offer a layer of strategy to the mix.
Proposal:
Classic pokemon games were released in different versions and each version had a unique set of pokemon that could only be captured in their respective versions. Therefore, I propose we split Illuvials into 4 sets... 1 common set that is available to all players and serve as an f2p set, and 3 other sets requiring a different fuel type for each set respectively.
We could then add the ability to enter stages using not just Crypton, but also Solon and Hyperion. So if I want to do a Solon run, I would enter the stage and the pool of Illuvials that can appear are restricted to the common set and the solon set. This change is minimally invasive, forms a strong use case for 3 fuel types, and allows for the inclusion of an f2p community which will boost the player base significantly.
Going more in depth:
This concept can be further expanded into the rest of the Illuvium world by having each fuel type adhere to a set of themes or qualities. For example, Hyperion could represent the qualities of strength, persistence, and physical power. So the warrior type suits and weapons would use this type of fuel or resources found from Hyperion stage runs.