Rome after III century

The romanistic liguists explains that romanian and sardian
languages remained "archaic" because of their position at the
extremes of the empire and more, because of their isolation .
This was accentued by the fact that Rome, after the III
century could not impose anymore the new lingvistic
innovations in the far situated province.
That maybe be the true.True is too the fact, the romanian
language is archaic regarding latin terms:-)
But this is a statement which make me to put some questions
regarding the romanians. We have 3 posiblities until now of
ethnogenesis of romanians:
north of Danube, south and north on the valey of Danube, south
of Danube.( somewhere in Balcans)

If the romanians are formed just in north of Danube the Danube
is the only factor of isolation from empire and this isolation
can be explained.
If the romanians are formed both, south and north on the valey
of Danube, it indeed matters how many people could take
contact from a side to another side for getting or changing
informations and if so they could develop the same languuage,
but a part of them was still in good contact with the empire.
The last suppositions anyway implied both at last a part of
rumanians in south of Danube. And here is the problem.
The romanians from south of Danube have not been isolated from
Empire. They have had a long dry-border with Dalmatia , they
was in the vicinity of Illiricum, in fact in the mddle of all
theritories supposed to be for long time and strong romanised.
Admiting the Roseler & Co theory that the romanians are formed
somewhere in the Balcans, we reduce the distance between them
and Roma again.
So , normaly, the rumanians should have been the first , in
the same position as the galo-romans for getting inovation
from Rome, and not at all "lost at the enge of empire".And the
rumanian language should have had the new lingvistic influence
from Rome. But the langauge, does not have the new words.
In this case something is wrong in the last 2 suppositions and
I am afraid dear Piotr, you will lost your money if you put
south of Danube as romanian cradle.