Despite the above-quoted texts (both from the Quran and from the Sunnah), I would never say that there is absolutely no hope for Satan.
I believe that the following ayah gives some hope no matter what:
On the day when every one will be resurrected and the jinn will be told that they have made many people go astray, their friends from among people will say, "Lord, we benefited from each other until death approached us." They will be told that their dwelling will be fire wherein they will live forever unless God wills it to be otherwise. Your Lord is All-wise and All-knowing. [6:128] [translation by Muhammad Sarwar]
A most logical way to understand should be this: from the point of Divine Justice, those people deserve to stay in Hell forever. Yet, if Allah wills otherwise, nothing can stand before that Will—not even Divine Justice. The ayah gives hope not because Allah says what He says, but because He says it right after about the of Hell.
The next quote gives even more hope:
As for the wretched, they shall be in the Fire, wherein there shall be for them moaning and sighing, therein dwelling forever, (106) so long as the heavens and earth abide, save as thy Lord will; surely thy Lord accomplishes what He wills. (107) And as for the happy, they shall be in Paradise, therein dwelling forever, so long as the heavens and earth abide, save as thy Lord will—for a gift unbroken. [11:106-108]
Note that Allah, again, when talking about people of Hell staying there forever, He notes that He does whatever He wills. But when He talks about people of Heaven, He simply says an unbroken promise. This time Allah avoids saying Allah does what He wills. Most certainly, Allah does what He wills, but He does not want people of Heaven to fear that because Allah does what He wills, He may, for example, expel them from Heaven; instead He reassures them saying that His promise is going to be unbroken. Again, in a sense, Allah is saying that His promise is such that it comes before His will.
In the light of these, I wonder how anybody can forever be hopeless from Allah's boundless mercy.