I'm not ruling out a delivery miss, but this post is highly speculative. You're saying that Tesla would need to deliver at least 30k MX to meet 80k total deliveries, implying that they're selling a flat 50K MS this year. That would be a decrease from last year's total, despite the fact that Tesla has increased MS deliveries each of the past two years by over 50%. Obviously Tesla can't sustain that growth, but predicting a decrease in deliveries this year? Very unlikely.
You're also saying that there's currently a 6-week backlog (longer than MS), but they will only deliver 15k this year. This implies that almost no new orders will be placed/confirmed and that they will only deliver about 4.5k MX in the entire second half of the year. The X will gain an enormous amount of additional popularity this year once more of them are seen in the streets/showrooms, popular reviews start pouring in, and celebrities are seen with them (check the Bill Gates video on the MX forum for example). On top of that, you're forgetting about the tons of reservation holders who are waiting to see/test drive it in person, or are simply waiting until all of the quality concerns have been resolved.