I must admit, I too, was thinking about Malakai at 12 with Paolo at 13. Does anybody know if Malakai played much at 12?
12 and 13 are very different roles. What we will lack at 12 is someone like Le Bourgeois, but who can mix it up with kicks and changes of direction/plan. That is, react to what is in front of them. That player is Jimmy, but that cannot be for much longer. None of those mentioned (in house) can do this, and nothing I have seen of the younger players does either. That was why we signed Mills, but at the time the injury prone nature of Mills was writ large and should not have been ignored. Fekitoa and Odogwu are both ideal 13 material, but not 12s. Same goes for JdeJ (although I don't see him being kept at the next end of contract). Spink is much the same. Will Simonds I see as more of the full height full back we need; good in the air and running, but his kicking game is also lacking.
What we need is a rare commodity in Northern Hemisphere rugby, but is fairly common in South Africa and New Zealand. So, as JdeJ, Jimmy and Mills go, we need one, maybe two imports. And, maybe, start to look to recruit at the U18 level for that style of player. 12 (and 13) cannot be seen as merely a conduit between 10 and the wings, but that is how English rugby sees them right now. It wasn't so when I was playing (just before they invented cars).