I'm skeptical Chantal even has thought that out, or only done so in passing. She seems pretty fucking dense when it comes to this diet thing. I really believe she expects the weight to just melt off her in weeks - if not days - of her starting a new diet. There's no better example of this than her video from April, 2018, which now has been deleted, where she's driving around town and talking about how she is going to lose weight that spring/early summer for the bachelorette party she was going to in four months (we all remember that mess). Her goal was to lose enough weight to look sexy af and she was going to buy a corset for the occasion. Of course, none of it happened, but it really showcases that mindset. She really expected she'd lose enough weigh in four months to wear a corset and look sexy ... and, of course, none of it happened. In fact, I'd wager that's her biggest problem. She's completely unrealistic in her goals, and expectations, so when, after a week's worth (or maybe even a few days worth) of doing what she's doing, and she hasn't seen the actual change she expected, she reverts back to her old habits and forgoes THAT diet for another one. It's a constant cycle.
Of course, it could start melting off over the course of a year if she actually just counted her calories ... but that's too much work, and, again, the initial payoff isn't there.
So, I doubt Chantal has even thought of the excess skin she would have after losing 200 lbs. That video from April of last year underscores this: her expectation is that it'll melt off and she'll look, in her words, 'sexy af'.