107.[/B][/COLOR] They will dwell therein for all the time that the heavens and the earth endure, except as your Lord wills. Verily, your Lord is the Doer of whatsoever He intends (or wills).
108. And those who are blessed, they will be in Paradise, abiding therein for all the time that the heavens and the earth endure, except as your Lord wills: a gift without an end.
According to Tafseer Ibn Kathir, the mention of 'except as your Lord wills' for verse 11:107 above is for people of Tawhid (not necessarily Muslim but someone who believes at least that there is One God/Creator with no partners).
"It has been said that the exception mentioned in this verse refers to the disobedient among the people of Tawhid. It is these whom Allah will bring out of the Fire by the intercession of the interceders.
Those who will be allowed to intercede are the angels, the Prophets and the believers. They will intercede even on behalf of those who committed major sins. Then, the generous mercy of Allah will remove from the Fire those who have never done any good, except for saying La ilaha illallah(There is no god but God) one day of their life.
This has been mentioned in numerous authentic reports from the Messenger of Allah, including narrations from Anas bin Malik, Jabir bin Abdullah, Abu Sa`id Al-Khudri, Abu Hurayrah and other Companions.
No one remains in the Fire after this final intercession, except those who will remain there forever without escape. This is the opinion held by many of the scholars, both past and present, concerning the explanation of this verse." [1]
And the mention of 'except as your Lord wills' for verse 11:108 above is also because God is the ultimate authority to decide on the pleasures He bestows on anyone and He can give you more than what you deserve.
"The meaning of the exception that is made here is that the condition of eternal pleasure that they will experience therein is something that is not mandatory by itself. Rather, it is something that is dependent upon the will of Allah. Unto Him belongs the favor of immortality upon them. For this reason they are inspired to glorify and praise Him, just as they are inspired to breathe." [1]
At the end, "Allah soothes the hearts and affirms the intent, by His saying" - 'a gift without an end'. "This has been mentioned so that the suspicious person will not doubt after the mention of the will of Allah. Someone may think that the mention of Allah's will here means that the pleasure of Paradise may end or change. To the contrary, it has been decreed that this pleasure will truly be forever and will never end. " [1]
Finally, even if one doesn't take the mention of 'except as your Lord wills' for verse 11:107 above for people of Tawhid only (i.e it can apply for anyone), it certainly is not a firm guarantee of a finite punishment but rather a possibility only according to the wisdom, justice and will of the Almighty and who knows after how many thousands of years of punishment in Hell. So I wouldn't be too excited on that account per say
. Better to at least believe in One God unless you have concrete proof otherwise.
Peace.
[1]http://www.quran4u.com/Tafsir%20Ibn%20Kathir/011%20Hud.htm