It's a lot more engineering work than you may think to switch battery cell chemistry from NMC to LFP. The heating profile and ion conductivity are vastly different between the two cathode chemistries. It will not be as simple as just making a cell with the same electrode layer thickness as existing cells. Much thermal modeling and testing wiould be required, and then you have to ask yourself "what are the potential gains?" vs just building more of the exisitng prismatic cells.
There's nothing magical about the 4680 cell format: it's an engineering compromise that was chosen specifically for Tesla's nickel chemistry cells. I don't expect any movement before 4680 production is fully ramped with the existing design. After that, why not another clean sheet of paper? Reinvent the wheel only when the wheel costs too much, is too hard to build, or is in some other way unfit for purpose.
Cheers!