I really hope that the Renault can be competitive next year, if it is, not only will we see a competitive McLaren, but also bodes well as Red Bull and Renault themselves will be closer to the front runners. The factory Renault team has improved massively over last year where they could barely score points to being easily in the top 10.
Things are looking well for them, the new sponsorships will help funding to develop the car.
I think that McLaren has taken a very pragmatic approach, when 2017 started the car looked rather basic, and it was, because they spent a lot of time working on the fundamental chassis for these regulations. The chassis and general aero concept was very well developed, and the complexity was added as they verified their concepts. The results have been obvious with intricate details sprouting around the diffuser, bargeboards and front wing. This methodical way of developing the car may not make the fastest car at first, but it ensures that only steps forward are taken. Whereas if you start with a more complex car it becomes increasingly harder to take steps forward as it takes more time to validate the increased complexity.
If the engine is competitive, Alonso will be able to fight for wins, if the engine isn't on the same level he may still get podiums and have nice battles with Renault and Red Bull. I do think the McLaren aero is on par with Red Bull.