In the ever repeating discussion about listening to current teams vs planning for the future I have to side with the future prospects.

Current teams will favor a solution which is cheapest to them at the moment and gets the maximum return for the (already invested) money.

As mentioned by Dirtfish themselves any current team can suddenly disappear. In fact, it's the usuall progress. Every team that has been there disappeared after a few years, either fast (if they are not competetive) or slower (if they are competetive and dont see the point of getting 5th, 10th, 15th title).
Only MSport breaks that rule and that's cause it's a private company and not a manu team.

With hybrid rules WRC can for once be somewhat on the curve of "progress" (or "change" if that's what you prefer to call it) in the automotive industry. Even though as was said first Prius was introduced over 20 years ago. How exactly the rules should like is off course another matter. For me electric-turbo only with some small battery would also work.
Change to R5+ without any hybridization is a road to (unlikely) short term gain (1-2 years) and long term oblivion. In that case I'd even say it's better to postpone the introduction of hybrid rules by one year and just keep the current ones until then.