WI Vandals remain in Spain instead of moving to Tunisia

[Zurirach Adankar]

What if the Vandals remain in Spain, never moving to Tunisia.
What are plausible reasons for the Vandals to remain there?

How would this affect the Western Roman Empire? Will we see a slower decline due to more secure grain supplies?
Would the Eastern Roman Empire try to capture Tunisia from the Western Empire?

Could we see a Roman Successor State in North Africa?

 

[Mildtryth]

What are plausible reasons for the Vandals to remain there?

For context, there were two groups of Vandals who settled in Spain, the Hasdings and the Silings, and in additon to them, there were also the Alans, a completely unrelated people, who settled in the south of the peninsula. Then Wallia, the Visigoth king, signed a treaty with the Empire settling his people on Aquitaine in exchange for military service, and he went to work quickly - he defeated both Silings and Alans, while the Suebi, who were allied with Rome too at this point, defeated the Hasdings, and then, the remnants of these three groups had to band together and flee the peninsula.

 

[ghappy1000]

The Vandals staying in Spain instead of moving to Tunisia might mean that the Vandals would be defeated, which would leave the Western Roman Empire with more secure grain supplies and one less enemy, which, in turn, would prolong the Western Roman Empire's survival without capture of Tunisia by the Eastern Roman Empire nor a North African successor state of the Romans.