I think you're mixing up ILBs and OLBs, which are two very different positions in 3-4 defenses. OLBs or what I prefer to call them "edge defenders" which are Greenard, Van Ginkel, and Ward (Hunter, Davenport, Wonnum, Jones II last year). The first two will likely be every-down players with Ward rotating in, with Jones II and Andre Carter competing with him and any rookies (I would like another 4th/5th edge).
At ILB, Flores tends to play two at a time but does situationally have only one out there as they opt to go with a safety or a third edge defender (Wonnum/Jones II last year). Cashman is likely stepping into Hicks' role as the every down ILB and Pace Jr. will continue his role as a weapon to be used 20-90% of the snaps depending on what the gameplan is. There were games where Flores only had him out there 10-15 snaps, and some he played nearly every down. The 5th LB you mention was Grugier-Hill, who should strictly only be a special teamer while Asamoah will compete with him. Flores showed zero faith in Asamoah last year so I expect we will not see any 3 ILB formations, just like last year.
So I don't see Pace Jr. being a trade piece, as there isn't anybody behind him that Flores would trust to fill his role. And with how well Ivan played last year, they'd be foolish to as I don't think they'd fetch much as teams don't often trade ILBs. My question is will Metellus continue to play an every down role as a 3rd safety? Flores did mention that they want to scale back Harry's snaps so it is possible Metellus begins to take over at SS when Smith is not on the field. Not to mention will Flores trust his CB corps to field 3 CBs in the nickel? Last year Metellus was the primary nickel CB and they only fielded 3 CBs [by name] in dime formations.