Even if McLaren were to revert back to Mercedes PU's, I believe it would only be temporary. Ron Dennis' original view that only works teams will compete for the championship seems to hold true.
So if Mercedes was only a stopgap solution while searching for something better, how long would it take for a new PU supplier to be competitive?
As painful as it seems, sticking with Honda may be their best option here.
Some historical context:
Honda returned to Formula One in 1983 as an engine supplier for Spirit and stayed in the sport for a decade, at various times teaming with Williams (1983–87), Lotus (1987–88), McLaren (1988–92) and finally Tyrrell (1991).
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As an engine supplier, Honda made its World Championship debut with Spirit's Swedish driver Stefan Johansson at the 1983 British Grand Prix at Silverstone. Johansson qualified in an encouraging 14th place (although some 4.5 seconds slower than pole), though he would retire after just 5 laps with fuel problems. Johansson had given the Honda its on track debut earlier in the year at the non-championship 1983 Race of Champions at Brands Hatch (the last non-championship race in F1 history) where despite unreliability, the 1.5-litre turbocharged V6 engine dubbed the RA163-E had impressed with its speed. By the final race of the 1983 season in South Africa, Honda had begun its association with Williams where reigning (and outgoing) World Champion Keke Rosberg served notice that the Honda was on the pace by qualifying 6th, only 7/10's slower than the Ferrari of pole winner Patrick Tambay.
Rosberg would give Honda its first win as an engine supplier when he outlasted the field to win the 1984 Dallas Grand Prix and by the end of the 1985 season where Briton Nigel Mansell and Rosberg won the final 3 races of the season (Rosberg had already won that year's Detroit Grand Prix), it was clear that Honda had the engine to beat in Formula One.
https://en.wikipedia.org/wiki/Honda_in_ ... .931992.29
Granted, back then it only took them about two years to be competitive, but there were no restrictions on testing and number of engines at the time. Today's limitations really hurts in-season development (the wiki I have linked to above mentions just how much development and testing Honda did in those days), as does the testing ban.
I'm not optimistic about Honda's chances here, but I really don't see any better options for McLaren, so I figure better to ride it out and see if they can become more competitive over time.
