Imagine a combat system not too different from previous editions that relied almost solely on the use of the grid, but tweaked so that it works seamlessly for those fights where minis are not used or expected.
I would rather it was the other way around, relied almost solely on for ToM and tweaked took seamlessly with grid. Personally I think it's just a bad choice of words since they said before that 4e style combat system is slated for a module.
Imagine a combat system not too different from previous editions that relied almost solely on the use of the grid, but tweaked so that it works seamlessly for those fights where minis are not used or expected.
(Baked Tweaks are delicioius, by the way.)
My main concern with the agnostic approach is that ToM-compatible mechanics are a strict subset of grid-compatible mechanics, so an "agnostic" design is really just a ToM design. I like the features in 4E that basically require a grid to use properly. An agnostic design simply couldn't include those kinds of features.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.