but i guess since they literally kicked/assimilated the Britons out of Britain - a lot?

Nope.

The new analysis shows a modest level of Saxon DNA, suggesting that the native British populations lived alongside each other and intermingled with the Anglo Saxons to become the English.

There is some evidence in the study that intermingling did not happen immediately following the Saxons' arrival, but occurred at least 100 years later. This suggests that Britons and Saxons had separate communities to begin with, and then over time they began to merge [BBC, 2015].

The Anglo-Saxon wipeout theory is dead in Archaeology and genetics, because most white English people display a mixed Anglo-Celtic ancestry in analysis of their dna that gets more Germanic in the South East and More Brythonic in the West. In order for most of us to have pre-migration genetic heritage there have to have been Celts around for the Anglo-Saxons to mix with.

What this article says is that Anglo settlements were very Anglo in the early days, which... no shit Sherlock.