Higuain is quite far from impossible. He is actually quite possible.
1st Mourinho said the time is coming to choose between his two strikers. And he knows he can't keep them both happy. Since then Benzema is obviously the preferred guy in front.
2nd Zidane - if he has any influence in RM- would kill to see his countryman and fellow arab Benzema as a started. He was pushing him when he was in a dismal form I can imagine what it's like now.
3rd Real Mardid's presidents hate loosing, but the second thing they hate the most is winning with players signed by your predecessor/future opponent. In these days of dirty politics and money I am not even sure they still count in the same order. Perhaps winning is not important after all - especially given RM's recent record.
So having all those things considered there is only one realistic possibility preventing Higuan from leaving RM - Mourihno playing with 2 strikers. But even then the question lays if Benzema/Higuan are going to form a working partnership and by what I have seen the answer is more into the 'mehhh' category, then there is the fact RM can buy whoever they want to form that partnership and also that having two attackers would require CR7 to track back and stop shooting every time he gets a ball or be sold/benched ... impossible.
Yes RM are likely to sell Hiquain, but this is not why its impossible to become our target, its because of our current status, we are down the pecking order now, better options will appear for him, if and when he will become available.
Since calciopoli we never made such an acquisition and there are plenty reasons for that...
What we clearly need are 2 quality players in attack: A more prolific finisher than Matri, and a stellar RWF to displace Pepe. Without those 2 acquisitions we can forget about making any impact in the CL. Backup CM, a CB for cover, and possibly a LB if Caceres doesn't impress there, and we are set.
One of those 2 players will be Giovinco, him and Vucinic can handle our left side needs.
For the right side we can live with Quaq and Pepe. Giacch, EstiG and Elia are more than enough for fillers.
So our primary objective should be a prolific finisher. For various reasons (price, nationality, capability of signing him) this will be Rossi. A realistic option, that we could possibly miss if we waste to much effort on Higuain dreams and end up with Boriello.
For the midfield, there is always the possibility of bringing back Melo, if everything we want is depth, if we want a starter to eventually replace Pirlo, we should go for De Rossi, as his contracts expires and we could always boss Roma on the transfer front.
We should avoid making any deals with Fiorentina, as they keep owning us hard in the transfer market, making us paying fortunes who like impressive in their mediocre ranks, but kinda fail in our level...
Napoli was also wiser than us in the transfer market since serie B and they are improving by keeping their core players.
And for the defense, we need a starter, we will see how the Caceres thing will go through and then decide what to buy. As this is a starter issue, it should take priority over every other market, bar the prolific finisher.
So by recalling Giovinco, bringing back Melo, or sign De Rossi as a free agent, we have the possibility to make massives upgrades without spending much.
Those deals, should be closed likewise the Pirlo deal, before the transfer window even starts and let us time and funds to focus on the CF and LB/CB deals.
Giovinco, Melo or De Rosi, one prolific finisher at least as efficient as Rossi and one starter defender are not that hard to obtain with our usual budget and current prestige and perspectives.