I think he will just be a journeyman. The fact that he has cracked the Top 100 is a great achievement, and deserved as well based on his great run this year, but I do not think he has the quality to be a consistent contender on the ATP Tour.
In this way, I think he is sort of like Marcel Granollers. Both also have quite unorthodox games, and both are really good doubles players too. But in the end I think Marcel is the more talented of the two.
Without trying to downplay his achievements, I also think that Horacio's rise in the ranking is for a very big part due to two factors: firstly, he had a crappy year in 2008, so he had very very few points to defend this year. Secondly, he schedules really really well. He has been playing the weak South American Challengers, which offer similar points as the much stronger American and especially European Challengers. On hard court, he is much better than most of the others. Moreover, many of the clay events are played on altitude, something that really aids his game. If you look at the players he has actually beaten this year, there aren't that many big names, and you could consider his ranking as inflated in relation to his actual performances.
I totally agree with everything you have said, i only posted a thread to get opinions because i read an article comparing his year thus far with Bellucci and Schwanks last year, although as you hinted the qaulity of opponents and challenger events played etc has not been at the same level as the ones those guys played last year. I have to admit though i have noticed him winning a lot of matches this year but was stilled very suprised to see him at 97, was expecting somewhere around the region of 100 - 150 and the fact that he has only ever played one main draw match (loss to Petzschner) at 24 yrs of age is incredible. Anyway cheers for the response, Zeballos beat Chela today in three sets, i watched it and he played pretty well