I believe he was ditched last season due to issues with Tata paying on time. If HRT fail to make Malaysia I can see Tata reconsidering their substantial commitment at which time it's 'find a pay driver'.
I can see both Clos and Luizzi being in that car at some point in the season.
Jamie Alg may fancy putting himself in the shop window towards of the end of the season as well. I dont blame him for wanting to avoid the mess at the start of the season but being quick in a rubbish car still gets you noticed. It certainly did Riccardio no harm what so ever.