If Rossi goes in January or at the end of the season I don't think I would mind too much. Same goes with Finkler. Rossi still has the ability to be incredible at A-League level but just hasn't used it, and Finkler is now past it. Most importantly it would free up two visa player contracts, plus frees up what would be a decent chunk of the salary cap (in the case of Rossi) and also a Marquee contract. I know its very early in the season, but I don't think either bring enough to warrant taking up visa contracts or a marquee contract. While Rossi is still a starting CB, For me Finkler doesn't start ahead of either Vidosic or McGlinchey - rendering his Marquee wage and visa spot a waste. I would be much happier if we let both go and signed another quality foreign defensive/central mid to partner Paracki (Our midfield would be insane), and marquee foreign winger
I do not think you can seriously discuss Rossi and Finkler in the same breath. If Rossi goes at some point, I would miss his contribution greatly, and wish him all the best. Finkler, in his current form, not so much.
Durante is about the closest in quality to Rossi but has a few years older body. If Rossi is injured (or, as you say, leaves) then we have a real problem. Mullen is no Rossi. Fox is no Rossi. Doyle is no Rossi. Sure we have cover at CB, but we do not have another Rossi.
You say he has the ability but has not used it yet. I am happy with his ability as it is now, and so I do not need much more class from him than what's he doing already at present. Any other A-League club would have Rossi in a flash (well, maybe not Melbourne City, as they shop elsewhere), but he is more likely to return to Europe than to do 'a Bonevacia' on us.
In contrast, Finkler came to us as a "two for the price of one" when we got Kosta, simply because Victory were not interested in paying him as much anymore and he got petulant about it and he knew Ernie. From what I can see, Victory are ecstatic to get Kosta back now, but I do not think they would be begging Finkler to return. As he does not run much anymore, Finkler would really need to rely on his skill more than speed now, the way that Alessandro delPiero did when he was at Sydney FC. So far I have not seen much of that from The Fink, for example his free kicks were particularly uninspiring (Macca is better than Finkler at them right now). I am prepared for us to wait till Finkler recovers fully from his injury as he is rusty, but the signs from last season and this season so far have been underwhelming.