I'll just go ahead and leave this here. You can read the first part too, but the second post is much more relevant to your question. The Gaulish elements for the most part had already entered Vulgar Latin by the 4th century, particularly taking the place of Latin terms relating to agriculture and other various aspects of "folk life". It's interesting that this is the case as Vulgar Latin for the most part is typified as being a rather homogeneous language in spite of its wide territory and "common" demographic. Beyond some transplanted words though, the Vulgar Latin of the Gauls was largely that - Vulgar Latin.
I may have missed your point, but my question was - how and why did Germanic elements came to
Galia? As far as I understand you are only showing in your very well written and even more detailed posts, that Germanic tribes affected Vulgar Latin (more in some less in other areas) but it was still widely used after 5th century. It's nothing new to claim Latin remained
Lingua Franca for upper classes, Church, jurisprudence and bureaucracy until 19th century.
But what Dachs is saying is that Germanic tribes from outside of WRE had very little to do with it's downfall. What am I trying to establish is, that Germanic tribes had to cross the boundaries at some time (hence their effect on Vulgar Latin and later French language). Now, Dachs is not claiming they didn't, but it makes it look like it's not a big deal.
But why, why did Germanic tribes had to settle inside WRE boundaries (instead of just being conquered and incorporated into empire like Gauls did).
And if they had such an effect on Vulgar Latin and more importantly on later French language (much much more than Gauls, who were native to
Galia), then we must assume that at some point there were more Germanic people in
Galia than Gauls. Right?
If so, they had to have something to do with WRE's declining fortunes. Granted, they didn't just march in one day and took everything over. But can we accept the fact their presence was so much less of an issue for Romans than bickering of Emperors in Rome?
Dachs narrative is that ERE was just luckier with their leaders and that gross incompetence of WRE Emperors was an extremely big nail in it's coffin. Now, from what I've seen in modern governments (and in history books), on general and on the long run they're all more or less the same (in their competence/incompetence). Isn't that what theory of probability claims, anyway?
I still find it hard to believe civilizations can die out without any external interference (exept if they sacrifice their entire population or because of some natural disasters). Sure, we should forget hordes of Barbarians sweeping down from north and east. But, eventually they were there, weren't they? Even if it took them hundreds of years, they were infact important players in the story of WRE.
It doesn't mean they contributed to WRE's downfall strictly through warfare, their presence could just be that disruptance in WRE's social strata that made people drift away...