i'll look at your academic article about this tribes names correlation, thanks for that! (I give my thoughts without thinking they were a Bible extract!)
As I said, I don't necessarily agree in all with the Swedish origin for the Goths, nor do I dismiss it. As for the Goths, seeing they spoke an old Germanic language, so they did originate from the proto-Germanic urheimat e.g. South-Scandinavia/Jutland /Northern Germany (Nordic Bronze age to iron age Jastorf culture).
Also, as I said above, Gautr, Gaut, Gauti, Guti, Gothus and Geat are name forms based on the same Proto-Germanic root, *ǥud*.
Gautr, Gauti, Guti, Gothus and Geat are name forms based on the same Proto-Germanic root, *ǥuđ- (see God). Gapt is generally considered to be a corruption of Gaut.
The names may represent the eponymous founder of an early tribe ancestral to the Gautar (Geats), Gutans (Goths) and Gutes (Gotlanders).
Gaut was one of Odin's names and the name forms are thought to be echoes of an ancient ancestry tradition among Germanic tribes, such as that of Yngvi, Freyr and the Ingaevones.
http://en.wikipedia.org/wiki/Gaut
Andersson, Thorsten. (1996) "Göter, goter, gutar" in Journal Namn och Bygd, Uppsala.
http://listserv.linguistlist.org/cgi-bin/wa?A2=ind0009&L=gothic-l&D=0&P=8323
Just a close evident common linguistic and 'tribal' designations of both Geats, Gutes (and their two homelands Götaland and Gotland) and Goths but also in place-names such as Göta Älv/Götaälven (älven = the river) in Sweden as of all Jordanes classical believe.
My guess is that the 'ethnos' origin of them lies somewhere in between, that is some kind of 'Swedish origin' but that much was happening then. And since they spoke an old Germanic language, they came from somewhere into the area of the proto-Germanic language and culture i.e. Scandinavia, Jutland and Northern Germany, most likely near some of the places connected to their name.
Another East Germanic tribe -the Burgundians- also have several place names in Scandinavia connected to them such as Burgundarholm (old Norse name for the island of Bornholm) or Borgund in Norway (both likely derived from borg = castle).
Several different ancient Germanic tribes did not rename both themselves, their homeland, rivers and whatnot after Roman books they could hardly read, really far fetched. Rather they were generally the same 'core' northern Iron age people of whom named themselves into confederations after a river, a cheftain, or a 'montain', a tree, a beach, whatever they lived nearby, hence why we have so many "goths" or "burgunds" and why they share an etymological origin in the same word.
The fact is the Goths from Roman historical literature were an old Iron Age, unquestionable, Germanic tribe, its origin in mainland Scandinavia (Sweden), currently debated. It would not be unlikely that their ethnogenesis, meant the origin of Proto-Germanic root word, *ǥud* can still be traced back to some place in Jutland or Holsten (Northern Germany) and from there spread as happened during all Iron Age Germanic culture.
And that's why the whole origin of the Goths originated in Sweden is debated in somehow.
Only the time, recent studies and genetic testing will tell.
but concerning swedish = danish language origin, my selfmade knowledge of languages tell me it is an oversimplification - all of these languages are from old nordic germanic languages and show some reasonable diverging evolutions where swedish and norwegian dialects stayed closer one to another than to danish modern dialects and language - the prestige of some stage of sanish "tongue" history could have influenced swedish (as bokmaal of Norway) but as a whole the non-continental dialects of germanic are still closer within them except the Skane and surrounding southern swedish dialects which keep the marks of Denmark domination - I can mistake, it 's true...
Yes, but the separation began at the end of the Viking age, late medieval era. That is, 1000 years ago. Already the proto-Germanic 'dialect' continuum emerged during Late-Nordic Bronze age and early Jastorf period existed to 2000-2500 years ago. Hence my argument of a 'common' origin between Jutes, Gaets and Goths. This debate in recent years has become common among Swedish and Danish historians.
Scania, and the rest of Southern Sweden tips (where I come from
), really have a modern close Danish intonation and linguistic semantic for obvious historical reasons of that the region until the 17th century, was the core part Eastern of old Danish kingdom.
http://en.wikipedia.org/wiki/Skåneland