Texture streaming OFF, How mipmap LOD switches?

I understand that Texture Streaming is based on distance to camera and texture priority. If Texture Streaming is turned OFF globally, I then can assume that the highest mipmap level will be used based on my texture memory pool? However, if my texture memory gets maxed out, will the mipmap LODs still function and does texture priority still play a role?

In addition, Since disabling Texture Streaming does not affect Lightmap and Shadowmap mipmap builds, I can then also assume that the highest mipmap LODs will likewise be used until the texture memory is maxed out.

If texture streaming is turned OFF, how does ue4 determine which LOD to use when texture memory is maxed out? If Texture Streaming decides the mipmap LOD based on distance and priority, what rule does UE4 use when TS is OFF?