Is LSCatilina's view that we couldn't have Arab conquest happening without Islam universal on the board?
I don't think that's universal, I'm not nearly arrogant enough to say that : it is my viewpoint, tough.
Or do some believe we could we see Pagan Arab migrations and conquests end up more like the European Volkswanderung, with Arabs taking over the rulership and high nobility of the regions from Iran to Morocco, adding some flavor, given names and surnames to these countries but not displacing local languages and religions in most places?
I don't think that's a good exemple, actually. The whole "People's migrations" model is essentially a narrative one, directly issued from how Romano-Barbarians percieved their own historicity.
Long story short, Roman ethnography didn't saw other peoples as worthy of an history but intengible (Look at Tacitus's statement on Germania).
What did Romano-Barbarians scholars? They went trough the two big historiographical tales of the era, which is Aeneid and Exodus, and ripped them off like there was no tommorrow.
Frankish origin mythos is one of the obvious result, but Jordanes' accounts in spite of being more realistic-looking is such as well (and hence why everything it tells before the IIIrd century should be seen extremely cautiously, as all the Barbarian mythographical migrations).
It appears that while you did have various human groups moving around the IInd century, they certainly didn't formed really distinct peoples. Goths, for exemple and contrary to the nice-looking but mostly irrealistic migration map we all know, didn't existed as a people before the IIIrd century but formed a distinct political ensemble (formed out of Germanic, Iranic, Dacian, Gallic and Roman elements in Dacia) trough their relations with Romania.
Not only Barbarians peoples were romanized to a significant extent by the Vth century, trough the aformentioned symbiotic political relationship, but they were importantly made of provincial Roman elements (in the same time Roman provinces had a Germanic presence since the Ist century, trough laeti).
Eventually, it's not so much that they replaced the rulership and the nobility, that they became part of it in the IVth/Vth century. With the disapperence of the Roman state in the late Vth, Romano-Barbarian rulers (usually already integrated in some administrative and/or military hierarchy at this point) took more or less legally the provincial imperium and replaced it.
Rather than a conquest as Arab takeover of the VIIth/VIIIth was, meaning a proto-imperial structure taking over whole provinces, the Romano-Barbarian ensemble is more issued from a late Roman evolution.
Not that such evolution couldn't happen IOTL, or that a China-like evolution couldn't appear as well (with Turkic or Mongoloid peoples, for instance). But nothing looking like a redux of historical Arab conquest of the VIIth/VIIIth centuries.