I did LCHF for a couple of weeks when I got bored with SW and it occurred to me that there was a lot of crossover and many things work well on both plans.
Eg omelettes
Steak and veg/salad
salads
yogurt
Obviously you couldn't have weird diet shit like muller lights or hifi bars, but I don't have those anyway.
You just need to avoid the carbs and add the fat instead. Cook your steak or omelette in butter instead of spray oil. Use tuna in oil and full fat mayo on your salad instead of light mayo.
But just because SW no longer promote the old plans, there is no reason why they wouldn't work any more, if that's what you want to folllow.
There's also a lot of similarity with the Harcombe diet, which is mostly LCHF, but you can have a small portion of porridge or brown rice each day.
No diet is a magic spell, where you have to follow it exactly or else it doesn't work. They just work by mostly reducing carby sugary rubbish to tiny levels.
I eat quite a bit more cheese than SW allows but that doesn' seem to affect my weight loss as much as having slightly too much cake or alcohol.