Aside from the fact that an HD remaster is the only conceivable reason the first two BioShock games are unavailable for backwards compatibility on the Xbox One, many leaks over the last year or so revealing the BioShock Collection have been all but confirmed by another big leak today from 2K Games' actual website.
For a few moments, 2K hosted a page on their site for the BioShock Collection, which you can see below. No information was included on the page aside from the title, but this pretty much seals the deal on it.
This comes right after the release of the System Shock demo yesterday, so if this news has got you in the mood for the series or its spiritual siblings, you can download the demo from Steam and Kickstarter right now.