From Soft doing it inhouse comes ultimately from Bandai Namco PR though. Given their repeated mistakes with this announcement (HDR, PC discount, etc), and From previously saying they weren't interested in doing a remaster and to ask Namco Bandai, I think Kotaku's independent sourcing is more likely the correct one.
I think you may be mixing up your stories here, they
said they weren't interested in doing a Demon's Souls remaster but to ask Sony as it could happen with another developer. Though, Kotaku could still be correct, nothing, we've seen other than that one Kotaku article links to QLOP and Virtuos where as many other articles state From Software are the developer with the
Gamespot article even specifying "Dark Souls Remastered is being developed by From Software, the studio behind the original trilogy, instead of being outsourced to a third-party studio."
Edit: Actually, the Kotaku article doesn't specify Virtuos, that seems to just be coming from
Doctre81, and while i do believe him I think its best to wait to hear on an official announcement due to conflicting information from the publisher (despite their missteps with communication).