#4 Jon Jones
There is a precedent for a Light-Heavyweight moving up in weight to fight at Heavyweight. The current, reigning UFC Heavyweight Champion, Daniel Cormier has done exactly that.
In fact, at time of writing, Cormier was still recognised as UFC Light-Heavyweight Champion as well. It is expected that Cormier will soon vacate that title making the clash between Jon Jones and Alexander Gustafsson at UFC 232 on December 29, 2018, a title bout.
Get the latest updates on One Championship Rankings at Sportskeeda and more
Should Jones win that one and it is expected he will, then a move up to Heavyweight division to fight Daniel Cormier is a possibility, given Jones remains the only man to ever defeat him.
If Cormier should not be champion at that point, there is a high probability that Brock Lesnar will be. Lesnar and Jones have been talking about a potential UFC fight for years and given the opportunity, there is little doubt that UFC would not attempt to book this money making dream fight.
Jones will fight in the Heavyweight division in 2019 and could well end the year as it's figurehead.