R.J.
My godmother is a speech pathologist (aka the highest ranking in speech disorder people, with her doctorate and over 30 years of experience)... and her answer is YES. With early intervention *and* a good home environment (sooooo many of the kids she sees their problems are made worse at home by parents who neither research, listen, nor care that they are making the problem worse) most of her true stuttering patients have the stutter completely resolved while they're still children, and ditto most other speech disorders and delays. Every child? No. But most. And AS important as early intervention (according to her), is also parental involvement in the loving/patience/kindness realm. Ditto most of the other speech problems she deals with.
When my mum was harassing me about my son's speech (it was fine) my godmother slipped me a packet of information on all the various disorders that's about an inch thick so I could combat my mum with facts and specs. It's amazing how many are out there. A few are actual physical problems (mostly fixable with surgery, like the tongue not being free enough to make certain shapes, or the buccal/trigeminal/or facial nerves being defective in one way or another, or a cleft palate, or an ear deformity, or, or, or), but most are a disconnect between mind and mouth, or a fine motor problem (the tongue is controlled by fine motor, and just like learning how to write), or an emotional override, etc. The book also had all the TREATMENTS for each disorder listed. And overall, they were: "Well THAT makes sense, yeah, I can see that, well THAT would be a good idea for anyone, oh cool... never thought of that one."
I'm sure when you go in to see the pathologist that she/he will be able to pinpoint exactly what's going on with your kiddo in a manner of minutes (it's fun watching my godmother at swim lessons, she can tag all 40 of the children in various classes in under 30 minutes (in large part because at least half have no problem... so it's "Nope, Nope, Dys-latin-I-Can't-Remember, Nope, Nope, Either x or y, Nope, X, X, Nope, Y..." Once you have your actual diagnosis it will undoubtedly be VERY easy to treat ((ahem, time consuming and tedius, but not like adhd where one typically spends 10-20 years working on a daily basis)... and they'll give you your own specific packet of info with explanations, treatment modalities, tips, tricks, things to encourage, things to avoid.
The hardest thing (again according to my friend) for PARENTS is how frustrated their child gets. Honey, if you've been handling ADHD frustrations this is going to be a walk in the park.