As you correctly state, the loss of North Africa was a devastating blow, with Peter Heather describing it’s loss as permanently crippling the Western Roman army. Deprived of it’s wealthiest province, the West could no longer afford to maintain a large and comprehensively equipped regular force. The hiring of independent barbarian groups thus became a financial necessity, rather than an end point to a supposed century of “barbarization.” It is at this point, the mid-fifth century, that it is reasonable to characterize the Western army as comprised largely of non-Romans, serving in irregular units and immediately under their own elites. These irregular units were financially attractive, as they needed only a salary and to be supplied. No funds needed to be expended on training, or, critically, on equipment. Indeed, the Gallo-Roman historian Sidonius Apollinaris wrote that at the Battle of the Catalaunian Fields in 451, the Roman commander, Flavius Aetius, did not command a single regular soldier. While it is unlikely no regular troops were present, as a contemporary to these events, Apollinaris is generally a credible source. By 451, it is likely the Gallic field army had so shrunk in size as to become ineffective, with the bulk of Aetius’ army being comprised of allied and federate contingents.

That does not mean the Western army had become a paper tiger. As Aetius’ campaigns in Gaul suggest, Roman forces in this period could be effective on the battlefield, though it is worth pausing to consider the role Aetius’ own diplomatic skills in managing various pro-Roman barbarian alliances played in his successes. That said, these forces were nowhere as cohesive or professionalized as the army of the fourth century. The demise of the regular military system had a very negative effect on the security and political situation of the Western Empire.

So, to summarize, yes, during the reign of Majorian, a few regular units likely still existed. However, the loss of North Africa precipitated a collapse of the military system. The Western court turned to the hiring of barbarian groups as a cost-effective measure to provide for imperial security in a condition of fiscal scarcity. Irregular barbarian units weren’t hired because they were viewed as more effective than regular troops, but because they were cheaper.

One passage in the Life of Severinus of Noricum seems to capture the final collapse of the Roman army on the Danube frontier—this would be during the reign of Odovacar, a few years after the nominal fall of the western empire:

So long as the Roman dominion lasted, soldiers were maintained in many towns at the public expense to guard the boundary wall. When this custom ceased, the squadrons of soldiers and the boundary wall were blotted out together. The troop at Batavis, however, held out. Some soldiers of this troop had gone to Italy to fetch the final pay to their comrades, and no one knew that the barbarians had slain them on the way. One day, as Saint Severinus was reading in his cell, he suddenly closed the book and began to sigh greatly and to weep. He ordered the bystanders to run out with haste to the river, which he declared was in that hour besprinkled with human blood; and straightway word was brought that the bodies of the soldiers mentioned above had been brought to land by the current of the river.