If you do it with no pressure either way, just presenting it as an option, they do definitely start to move away from it in time. I think that excessive clinginess to an advanced age is caused either by some kind of extra need in the child, or a parent who carefully creates a situation where the child is aware that the parent is dependent on them, or when they always give the message that the world is a scary and dangerous place. You can be encouraging of independence while co-sleeping and using slings, it's a bit of a misnomer to think that you have to encourage independence by forcing something when they aren't quite ready for it. You can just keep giving them opportunity to try things for themselves and the independence will come. A good rule is that if they can do something for themselves and they want to, then let them even if it's inconvenient for you.
At six months independence might be feeding themselves, exploring finger foods by themselves, not overly helping them every time they want to reach a toy, etc. Don't rush in and try to fix frustration every time, it's okay for them to feel frustrated as it allows them to find a way around it for themselves. I am also a big believer in not helping them to do something they can't yet do for themselves, if it doesn't need to be done - e.g. I don't like those bumbo chairs which force them into a sitting position, or baby walkers, and I don't like walking along holding a baby up by their arms (to make them "walk") until they are at least cruising, and even then I think actual cruising practice or using you as a static obstacle to hold is more beneficial. Later on if they want to go on something at the park/soft play my rule (apart from swings) was that they can go on anything they can get onto themselves but I wouldn't help them up to higher things. Don't run straight to them if they hurt themselves, give them a chance to come to you first (unless it's something really bad or they can't move, of course!) When they start talking or signing, teach them a word or sign for "help" which is useful because then you know when they actually want you to step in and when they are just getting annoyed but still figuring it out for themselves. I know these sound perhaps a bit petty or small issues - and perhaps my line is drawn in an odd place, but it just always made sense to me. It might have been influenced by the book The Continuum Concept, but I don't really remember now because I read it so long ago.
DS is pretty shy and doesn't like trying new things, so it's not a cure all, but once he does try something, he's normally very confident and masters it straight away. And then he's fine. I noticed him first start to reject co-sleeping at around 10 months but he didn't reject slings until he could walk, which he did later (16 months - again mastering it within about a day or two) And then with both it wasn't a clear ending, there was a back and forth to it. But he's actively hated to share his sleep space since about five, and although he still likes being carried occasionally at seven, barely if ever asks for it. He'd much rather run. I don't really remember when it stopped being an everyday thing, obviously much younger than seven!
I think that you will see a natural tailing off of these things if you trust in the process and trust your baby to know when they are ready and to handle things for themselves. It's great to watch them learning something new.