Honestly, I think it really depends. So much more than scores/skills goes into long term gymnastics success. There are plenty of examples of middle-of-the-pack compulsory gymnasts becoming top optional gymnasts. But I've also seen plenty of gymnasts who have been successful all along.
Out of curiosity, I checked out my state's 2012 L4 state meet, youngest age division. It's a small sample size for sure, but interesting nonetheless. Of the top 5 finishers, four competed L9 last season and one had quit. Out of the middle 5, last season one was L8, one was L9, one was L10 and two quit. Of the bottom 5, four had quit and one was L10 last season. The only gymnast in the bunch to have competed last year at the national level (Easterns) was the L9 in the middle group. Based on this very limited pool, it seems that gymnastics longevity might be slightly greater among higher scoring compulsory gymnasts, but optional success can emerge from any of those groups (top, middle, or bottom). If I had more time, I'd check my theory against other years/age groups. But alas, I am not that dedicated to the topic!