What should be the main event for UFC 284?

For UFC 284 in Perth, Australia the UFC has not yet came up with the main Event for UFC 284. There are some fights that are official for UFC 284 but the main event is not yet confirmed. During UFC 280 In Abu Dhabi over a few weeks ago, Reigning UFC Lightweight Champion Islam Makhchev called out UFC Featherweight Champion Alexander Volkanovski In Australia. Because of the fact that Volkanovski is from and fights out of Australia and the fact they both have an interest in a Champ Vs Champ super fight in  Australia it could be a potential main event for UFC 284. As of right now, the current official fight that we know of is Costa vs Whitaker which I''ll write another thread about closer to the event.