DD could never sleep with her arms free, so we swaddled her til she was around 9 months (much to the horror of most people, but it was either that or go actually crazy with sleep deprivation!). After the first 6 weeks or so we only wrapped up her arms, but like your little one, it got to the age where we were a but worried she'd be swaddled forever!
At about 5/6 months, she started breaking out of the swaddle in the night, and at first we tried weaning her off (gradually loosening/just wrapping one arm) but it was pretty much a disaster, so we just kept finding increasingly secure ways to swaddle her, which she would fight as we were wrapping, but as soon as it was done, she would calm and fall contentedly to sleep, until some point in the night when she'd break free and wake herself up crying hysterically until sh was re-swaddled!
I'd love to share some magic method that finally worked on her, but actually what happened was that one night I woke in the early hours to find she'd busted out of the swaddle and was still asleep. At her next nap, I put her down in her grobag with her arms loose, and from then on she slept absolutely fine without it.
I just think she needed it for comfort until such a point as she simply didn't need it anymore, and weaned herself off. So really don't worry about not being able to ever stop. I guess like most things, some babies are just a bit later with some things.
She's 2.5 now, and a brilliant sleeper (most of the time). 