Not read the whole thread, so apologies for any repeated points.
I cant see VW entering - not from a cost perspective, but the reality of a heavily engine led formula and lack of available decent engines - Cant see Mercedes or Ferrari giving them engines. What would they gain? questionable how relevant F1 is from a marketing tool nowadays as the cars are so restricted - maybe there is a sense of it being the premier motorsport division, but in reality the benefits are not huge and the potential pitfalls of not doing well (hello Toyota) are clear.
Would love to see more companies getting involved, but its a different sport nowadays - and the engine rules need to change so there are less barriers to entry