Nobody plays DMC for a plot....well its there to explain why we do the things in the game and the fact every game needs one.
Its about DAT GAMEPLAY SON!
Nobody (but DmC fans) has faith in DmC since NT is at the helm of it.
Its overall potential as a whole and not in one simple factor.
DMC never became popular and so revered because it had a good plot. God NO! DMC came out the womb with a movie cliche plot D and generic writing 101 and people still loved the crap out of it and DMC3 is even revered to as the best action game of all time (by a lot of people not everybody).
Although its being debated if Bayonetta is better, a game with a plot as contrived and ridiculous as DMC.
Some thinks DMC5 has more plot potential (I'm not one of them) due to the fact all DmC is mainly doing to following what the old series done before especially with Downfall showing Vergil becoming corrupted and becoming like the old Vergil wanting more power.
Its basically just following what the old series done before with the whole revenge plot against Mundus and Dante's relationship with his brother as well as Vergil being corrupted for power. To some it seems DmC is going the same route as DMC3 so why waste time on seeing the same crap again but done differently than actually seeing something new.
I guess it has more potential since its going to copy what the original series had done before but do it differently. Vergil and Dante are most likely going to become arch rivals/enemies like the old series basically making a DMC3 2.0....although DmC was basically DMC1 2.0. Plus with how Capcom wanted to cater to old fans it seems likely they'll just turn it into the hold series.
Tomb Raider reboot holds more potential as it explores concept never before seen in the Tomb Raider world but all in while keeping very key elements from the old such as Lara....which is it really, new characters, new backstory, a new world, and thus forth it holds more potential as it can explore new concepts and not just do everything the old series did before it.
Both series hold equal plot potential as there are plenty of unexplored plot points in DMC and DmC left to explore as well as a lot of stuff they can do with the universe they've created. Plot potential is something that isn't set or determined but is based on the creators/writer's talent and ideas themselves.
A Sparda prequel won't solve any plot hole or question in DMC as a majority of the questions are directed to the present of the timeline. Well it could resolve some issues and questions such as who was the priestess, why did Sparda turn on his brethren, and why did create a Hell Gate in Fortuna.
Plus DMC's plot isn't a mess as some make it how out to be. The only real issues in the plot are Nero's origins (though stated and hinted to be Vergil's son can be clarified to at least Nero), Vergil surviving the attack (although funny thing is the DMC3 manga resolved that issue), and how did the Order find Nelo Angelo's fragments and Yamato (although someone at Capcom stated he found it near one of the Hell Gates).
Can you think of more?
I also find the concept of what in fact happened to Sparda's physical body interesting. If he did die, something became of his physical body no (was his body buried in a seclusive spot or to protect its secrets completely destroyed and if so by who since the anime and DMC2 and DMC4 hints to Sparda having followers or associates after defeating Mundus and sealing away the demon world).
Also Arkham hinted to the fact that humans created Temen-ni-Gru to gain access to the power of the Underworld so potential sorcerors and witches like Arius maybe even an entire demon worshipping cult who still exists after the events of Sparda sealing away Temen-ni-Gru.
Plus I want to see what becomes of Fortuna City and Nero and Kyrie since well their entire government was wiped out and they're left without a form of defense from demons and themselves and lets not forget since the one's responsible for the Order's destruction were Nero (and Dante but they don't know that) and I think the residents even looked to the Savoir for hope until well Nero crushed it so they must be extremely ****ed at him. Plus I think due to Kyrie, Nero most likely told everyone he is a demon or isn't afraid to show his demonic arm so now everyone must think he is a demon and probably remembers him as the demon who crushed their savior and killed their leader (Sanctus) and probably holds him responsible for the demon attack on Fortuna City due to not knowing the full story.
So a DMC4 sequel could follow Nero "enduring the exile" all the while trying to protect and help the people of Fortuna City although they hates his guts and could lead to more development for him.
I guess when Nero awakened Yamato and started speaking about enduring the exile might have been foreshadowing of events to come for Nero.