I think Mercedes want Di Resta to get more of a learning curve from a drive at Force India, the reason for that is that, i think, is that they think that he can become a better driver scrapping for P10 than scrapping for P20 with his team mate.
I think if push comes to shove Di Resta will go to Hispania, but Liuzzi will be under so much pressure to perform that he better perform out of his comfort zone and out qualify and out race Sutil its unbeliveable, otherwise he will be gone before the halfway point.
Im not anti Liuzzi in stance, i think he is a damnd good driver, i just think that he has had his time in F1 now, he has had 3 full seasons with Toro Rosso and Force India and has only out performed his team mate once in 2006.
If Liuzzi makes it to 2011, it will be with Hispania for the full season of for the first half of 2011 with Force India as i feel that Mercedes will be dictating the terms to him.
If Liuzzi is in the Force India seat, Mercedes will i feel put Di Resta at Hispania, reading him for the switch later on, then i can see Nico Hulkenberg takeover that Hispania seat as Hulkenberg is on the radar od Mercedes now, as im sure they would want Hulkenberg and Di Resta at Force India for 2012 with Sutil taking the step up to Mercedes in 2012 is Schumacher decides to retire.
Hispania have alot of things that will come to them, simmilar to what Minardi had back in the late 90s and early 00s with the likes of Alonso, Webber and Davidson coming to race for them with money from Briatore for the seats of Alonso and Webber and money from Honda for the seat for Davidson.
Also with the sale of Toro Rosso on the horizon, there will be more space and room for them to try and court the money from Red Bull for their Red Bull Junior Team drivers, and with one Carlos Sainz Jr in that team, placing him in a Spanish team in a few years time could mean the money from Red Bull and Spain could flow into the team then.
There is too many vageities fwith Hispania for the future, im sure all will be resolved in the short, emdium and long term future.