This is one of the toughest questions I encountered, it is always there, in every game I play, I feel like, should the franchise just end here ?!, or should we get more and more sequels ?!, let's discuss this at length over various franchises, don't worry I will avoid spoilers as best as I can.
First let's see God of War franchise, the first one was a game that grabbed so many gamers over night, the 2nd one delivered really great, then we got Chains of Olympus which was on PSP and was another cool title, and we finaly got the 3rd title, which in my opinion was the best God of War title to this day, GOW3 delivered in every aspect, be it boss battles, brutal executions, story, or graphics, it stands as one of my top PS3 games, but at the ending it felt like, well God of War ended, but then we got Ghost of Sparta which was another prequel same like Chain of Olympus, and now we are getting Ascension, which to be honest isn't my cup of tea, I know I am yet to play it, but a prequel on the PS3 doesn't seem right to me, we have been through most of Kratos history already, I feel like we are running the character thin by doing more and more prequels like this, I wanted a GOW4, but I am not so sure, should GOW have ended with the 3rd title ?!, Kratos seems to have fulfilled his role and more, so another God of War may make no sense at all, of course Santa Monica can suprise us with GOW4 but do we really need it ?!, I would be okay if Sony invested in Heavenly Sword IP to replace GOW, Heavenly Sword really got it, the first title had it's flaws like some really bad dialogues, but the combat had potential, and the flaws could have been fixed.
Now let's move to Uncharted, first game was really good, Among Thieves built alot on it to deliver a very cinematic experience, and at the end of both titles it felt like Uncharted can have more, it felt like a one adventure at a time title, we can have more, but then Drake's Deception came, it was great, but the story and how it settled kinda felt like this is the end Drake, this is your final adventure, even the ending felt like Drake you did it all, go rest now, and it left me wondering should Drake come back for Uncharted 4 ?!, avoiding spoilers if you played UC3 you would know what I mean, on the other hand there is The Last of Us developed by Naughty Dogs too, but it isn't the same game, so should Uncharted end ?!, or should Drake end and a new protagonist rise ?!, I am arguing that the developer in order to give a personal story, ended up driving Drake to a corner in a sense.
Another series that comes to mind is Splinter Cell though in a very different light, Splinter Cell doesn't need to end, but it felt like Conviction was the end of Sam Fisher story, I was hoping for one last epic ending for Sam in Splinter Cell 6, but the developers turned him younger and immortal, they also changed his voice for MOCAP reasons, and it left me wondering, should I have settled for Sam Fisher story ending at Conviction instead of hoping for another title ?!, I didn't want this, I wanted a new agent to be introduced in SC6 to be the main character after Sam in SC7, but it seems that won't happen any more, but some series need its main character story to end and a new agent to come, right ?!
There is also the other side of the coin, games which have sequels, but those sequels aren't direct, the sequels comes from the gameplay perspective, and here is where BioShock comes to mind, if you look at BioShock Infinite it is nothing like the first Bioshock title, but it got the same gameplay of using supernatural powers along weapons, set in a different setting and with a different protagonist, it carry on what Bioshock introduced while at the same time improving with new features, that way we can still enjoy the same awesome gameplay and amazing setting, while having new stories and new experiences, all of that without suffering from driving the franchise to the ground or losing the protagonist appeal.
Castlevania Lords of Sahdow had an incident as well, it was one of the most amazing games I played, and a little while back Mercury Steam said that CLOS lore will end with Castlevania Lords of Shadow 2, I was quite surprised, CLOS was amazing and it had great potential, I was sad, to be honest I wanted more, but at the same time I respect how the developers felt like they need to make a solid story, and revolve the game around 3 titles ((Mirror of Fate on 3DS included)), rather than water down their hard work, they wanted to end it in a grand fashion.
There are alot more Franchises that we can discuss, Resident Evil, Dead Space, Resistance, SOCOM, Syphon Filter, Legacy of Kain, Darksiders[/b], alot of games where sometimes ending them would be the right move, or rebooting them would be better, or just starting with a new character would be the best choice, too many games to discuss, maybe I will do another part to discuss the other franchises, I don't know.
So what do you think ?!, cause personally I got some franchises that I love so much, I don't feel like I am okay with them ending, while I also fear they may become a shallow shadow of their former epic self, so whenever I play a franchise and reach a title where the story feels like this is the ending, I ask myself, should it end here ?!, or should it just go on ?!, a hard question that most of the time I find no answer to.
One last note, I believe my fears come from the fact that there may be nothing that would replace franchise X, like for example Tenchu, I am still waiting for a new Tenchu title, I don't want Tenchu to end, cause wherever I look around I can't find a title that can replace Tenchu, heck I wouldn't mind rebooting it, but forgetting all about it seems like a waste, especially since Tenchu was one hell of a ninja game.