The likelyhood of her developing abscesses will gradually decrease as her feet are trimmed back into shape. Any horse, shod or barefoot and cared for by the best of farriers can get an abscess on occasion, though it's not common and a steady string of them would indicate there's a problem.
I've seen some really neglected feet turnaround and not bother the horse once the trim was fixed. There is potential for long term damage to show up later, in the form of arthritis, etc from cumulative damage on the soft tissues in her legs from the funky mechanics of a neglected foot. However, the prognosis is still pretty good. Once you set them up with good trimming, the body is able to function smoothly and even permanant damage can cause little to no lameness, if trims are maintained from here on out.
So, yes, there's some potential issue lurking about that could haunt this mare. But, getting the hooves fixed up to what she needs may eliminate any symptoms in the future and stop further damage and you'll never be able to tell she reached this point. Or she could have arthritis develop as time goes by. If's she's not lame now, then I wouldn't worry too much about it, she's likely to be fine. I've seen some gnarly hooves trim up and the horse was just fine after that, but horses that had been trimmed their whole lives and shod by "top " certified farriers that had more cumulative damage and arthritis than some of the neglected horses. It just depends on the individual and how his body responded, and how he was able to use himself, inspite of a deformed hoof capsule.
For the suggestion that you do it yourself:If you have a qualified trimmer, I don't see why you would need to start doing it yourself every two weeks. Let the professional do their job, unless they suggest you "tweak" the trim between visits. The few things you would learn scratching away at this horse every couple of weeks is not going to compare to the variety of hooves and problems your trimmer has been trained to deal with and has already experienced, and it's easy to create an imbalance if you don't know what you are doing, which is why I don't suggest people do their own horses just because they are barefoot.At least shoes stop some people from messing with them. I get to fix problems all the time that OWNERS created when thought they could trim their own horses after they read an article on the internet. Please, if you want to do your own, get hands on instruction or formal schooling.