In the new system you cannot strictly draw a line between SP and MP and the AI, because the AI is getting more a part of MP, compared to 1946 (without mods).
Therefore I would love to see better AI, but what is better AI worth, if the netcode cannot support more than 15 AI planes in a coop mission, otherwise the planes warp, lag or are not drawn at all (see ghost/phantom planes)? Seeing improvement of the AI as long term project, I would first focus on the obvious problems and bugs:
FM (performance of the existing planes before introducing new ones f.e. service ceiling
) -> SP&MP
Network (get rid of the ghost dots and warp-fest of AI) -> MP
LOD (dots visibilty) -> SP&MP
AI -> SP&MP