Different time, back in end of 60's early 70's, there's a need from US to get some examples of Mig 21. The earliest example according some sources, did come from TNI-AU inventories. However at this time around, US can get examples on Flankers from various sources.
If Indonesia want to get rid of TNI-AU Flankers, is most likely selling them to other users. Vietnam come to mind as their Flankers are in similar config with TNI-AU ones. However I don't think it will happen. TNI-AU need more active numbers of Fighters Sq's. So I think they will used them for at least another decade, until something come out in next decade as replacement.
Up until early 2020, what TNI-AU talking (even some leaks on their presentation to Parliament) was F-16V and LCA like FA-50 as Hawk replacement. However they seems now want to refurbished all F-16 and Hawk to make it available toward end of this decade or early next one. This I suspect cause the Political choices of Rafale and/or F-15E or even Eurojet can't be afforded at best to reach 10-11 Sq Fighters plan, if they retired those Hawks, Flankers or Older F-16.
The talk of F-16V or FA-50 is more the hope of some defense enthusiasts like me, that concern with TNI-AU operational sustainment. However seems the Political lobby take another direction. Even Boeing FB page shown F-15E when they congratulating TNI anniversary last month.
View attachment 48667
Not saying this's what will be procure, still need a lot off US Lobby on this. However it's showing the lobby is in that direction with US. Indonesia keep in the position if US do not want Indonesia getting Su-35 under CAATSA, then either allow Indonesia to get F-15EX or F-35. Indonesia in the lobby with US reject F-16V so far instead as US offer.
Don't know if the procurement include in this talk in Manama yesterday. Still it's means the lobby still ongoing.
So the way I see the lobby moving at this moment, MinDef still want to get the target of 10 fighters Sq's from current 7 (2 F-16, 2 Hawks, 1 Flankers, 1 Super Tucano, and 1 TA-50 as LIFT and Light Attack). However seems the additional 3 sq will come more and more with Rafale and F-15EX. Frenchie already agree on Rafale, and what's left is the negotiations on financing costs. While with F-15EX, what's left if the lobby get approval from US.
All this will still make a Hodge pot of Small numbers of Fighters type that will not helping TNI-AU operational sustainment costs. It will not be an Ideal operational Air Force fighters fleet, but seems will make 'ideal' Political fighters fleet.
I'm still hoping some sanity check until last moment. However I do afraid so far the direction is not going there. As for KF-21, well despite all the talk and negotiations on KF-21, I always remind to those who's optimistic on this project. Follow the money trail and not empty negotiations. If they go with Rafale and F-15EX, is there any budget left for this KF-21 Project ?