Let's tackle an issue here; Lando Norris. What has he done to warrent the massive hype going on around him? SKY have been building his reputation for about a year now. I do not regularly watch any junior racing categories but I do read the headlines. I don't get the impression he is the new golden boy.
Vandoorne for that matter was massivly more impressive before he arrived to Formula 1. Why would Norris fare any better against Alonso than Vandoorne does? And does replacing Vandoorne for Norris warrent the minimum one year get-up-to-speed time where Mclaren will have to rely on Alonso to drag home the points?
Actually, I'd question if it is right for Mclaren to put another rookie in that 2nd seat. Can they really afford the lack of points from their second driver? Other big teams, such as Mercedes and Red Bull first station their junior drivers elsewhere to get experience. Mclaren would in my opinion be wise to do the same, if possible of course. Ferrari has now done the same. A top team doesn't have the time to wait for rookies to mature. Basically only Hamilton has succeeded as a rookie in a top team.
I'd say Mclaren should go shopping for a good nr2 driver. Chances are they'll have to swallow their pride, but I'm sure they're used to that by now. Drivers like Magnussen, Perez, Hulkenberg, Sainz would be solid and a known quantity. Mclaren could even take a loan on Ocon if Mercedes would allow it. Either way, Mclaren can't afford to run another rookie.