How exactly would a Unity 5 update affect KSP?

[NoMrBond]

also what version of 4 do i need?

I recommend 4.2.2 (from the archives) if you wish to make mods for KSP, as this version works best with PartTools 0.23

[Eric S]

I'm not sure what version of Unity 4 KSP is currently running on. As for whether or not the devs are changing to Unity 5, Unity 5 came out after the KSP 1.0 dev cycle was well under way, so it was too late to switch to U5. The devs have stated that they're excited for the possibilities that U5 bring, and that they will be evaluating the feasibility of switching to U5 as soon as 1.0 comes out (to be clear, the evaluation will happen after 1.0 comes out, the timeline of a U5 port would depend on that evaluation). While many games have already switched over to Unity 5 and some have taken very little effort, most of the games where the devs have reported problems converting to Unity 5 have more in common with KSP than those that had an easy time, so I suspect KSP may fall into the category of games that didn't/won't have a smooth transition.

[NoMrBond]

I'm not sure what version of Unity 4 KSP is currently running on. As for whether or not the devs are changing to Unity 5, Unity 5 came out after the KSP 1.0 dev cycle was well under way, so it was too late to switch to U5. The devs have stated that they're excited for the possibilities that U5 bring, and that they will be evaluating the feasibility of switching to U5 as soon as 1.0 comes out (to be clear, the evaluation will happen after 1.0 comes out, the timeline of a U5 port would depend on that evaluation). While many games have already switched over to Unity 5 and some have taken very little effort, most of the games where the devs have reported problems converting to Unity 5 have more in common with KSP than those that had an easy time, so I suspect KSP may fall into the category of games that didn't/won't have a smooth transition.

KSP 0.90 is currently running on Unity 4.5.5*, we have no indication what version KSP 1.0 will launch on, it could be anything up to 4.6.4 or any of the prior 4.6.x versions or even remain on 4.5.5 so they can skip the 4.5.5 -> 4.6.4 rigmarole and skip straight on to the big 4->5 leap.

*According to the version information in the KSP.exe

[gendalf]

DirectX11

does it mean that dx9-10 gpus won't get an affect or won't be able to run the game?

[Eric S]

does it mean that dx9-10 gpus won't get an affect or won't be able to run the game?

Pretty sure it means that they won't get the benefit, not that they won't be able to run the game.