Because the club would look extremely, extremely, extremely bad if it didn't go through after announcing it so it must be water tight and therefore will go through.
But that's exactly my point. We will indeed look stupid if it happens.
The intentions from our club to sign him might be good, but the effect of us going into meltdown this season (if that should happen) might not have been accounted for in the contract with Keita.
Again: The failure of not signing players essential for use this season can't be rectified by signing (or looking to sign) players in the future. We haven't even paid for him, so for me it's just as saying we might sign Bale, Ronaldo and Messi in the next 3 upcoming summer transfer windows.