If they stopped there, it's very possible that Gothic and Vandalic languages might last a bit longer in the west, and we can see some further written traces, perhaps a lasting language for a few more centuries, with Spanish being more influenced by Gothic than Arabic. At some point, I would suspect that the Arianism of the African Germanic tribes would be stamped out.
One question would be, how would Spain develop without the unifying force that was the expulsion of the Arabs, lasting till the 15th century? What about Portugal? The Goths could be seen as a parallel to the Normans in England, shifting the Spanish language with a large vocabulary of Germanic terms, maybe even replacing core lexical items like pronouns and affecting inflections. That would be interesting to see how that would develop.
Given that the Arabs are still around here, the age of exploration is still very likely to occur, +/- a few years. With the Germanic tribes not overrun in Africa, they might tie in with Europe and make at least northern Africa a bit more developed as of 2012 given the cultural ties and similarities between their cultures.
Taking it to the present, one possibility: Vandalia is an African republic, with its capital at Carthage, speaking an East Germanic language with a number of dialects, to various degrees influenced by Gothic Spanish, Italian, Latin, and Sicilian, and some Berber words. The Byzantines did not ship them all back to Constantinople to replenish their armies, instead relying on Goths and Slavs to the north. This paved the way for the Vandals and Hispanic Goths to aid the stop of the westward expansion of the Arab armies. Its territory covers most of the coastal region of northern Mediterranean Africa, while Spain's territory covers its European land along with much of the western coast of Africa, aside from the Gibraltar regions, owned by the United Kingdom.
Languages: Portuguese (about 70% Latin, 28% Gothic, 2% other); Spanish (58% Latin, 40% Gothic, 2% other), Vandalic (75% East German, 18% Gothic, 7% Romance); Spanish and Portuguese re-assimilate the comparitive/superlative from Latin under Gothic influence, unlike French and Italian; the article become þa (f), þo (m); þos (pl), relative þai, þoi, þois; verbs merge towards the following: a, is, i, amos, aþ, an in the present, ending now in o, es, e, amos, aþ, an with umlaut in the singular; strong verbs spread to Latin-root verbs; the 'to be' merges with Gothic as som, es, est; siomos, sioþ, sind; the verb wiljan replaces OTL querer. The adverbs ja and ne replace OTL si and no. "To go" is ganga, gangas, ganga; gangamos, gangaþ, gangan; past iddia, iddias, iddia, iddiamos, iddiaþ, iddian; future: gangé, gangás, gangá; passive: gangada, gangadas (d from other forms, -s from 2nd pres), gangada; future passive: gangadé; et al. Portuguese adds þreis (now þres) as a numeral, as opposed to Spanish tres; Portuguese prepositions include under, wiþra, and miþ; Spanish includes miþ, af (of, from a place, indicating motion, as opposed to de, which remains to denote ultimate origin). Negation for verbs is achieved by placing no (emphatic ni (es), ne (por)); sundro (various) (habemos þas sundras casas verdaba - we truly have the various houses (sp: verdamente)); portuguese preserves the gothic 'aba' more readily, while spanish use is mixed by dialect, influenced by French's 'amente' ending. Another: fundemos þos filios 'we found the sons'.
Map:
Possible, but just an idea to throw out there. Vandalia might be an interesting place to live, and this version of Spain might have a language a little easier to learn.