I may as well chip in on the speculation here, although with my track record I'll probably be proved staggeringly inaccurate!
First, as I've commented elsewhere on Cbn, I'd like to see the re-introduction of Blofeld & SPECTRE, though not simply transplanted, Mao style suit, Persian cat and all, from the 1960s to the 2010s. This villain and his organisation has to be reconfigured for the here and now, if at all.
That said, we may have a two or three story-arc consisting of either:-
(1) The return of Quantum and Mr White, who may be the head of that organisation, or may just be its shadowy enforcer on behalf of an arch-villain or a committee of villains. No involvement of Blofeld or SPECTRE at all.
(2) Quantum becomes SPECTRE. White may still be involved, but answerable to Blofeld, who was the head of Quantum all the time, and, as in the novel Thunderball, has terminated a previous crime/espionage syndicate when things got too hot to handle, only to re-emerge years later as head of SPECTRE.
(3) SPECTRE/Blofeld are Bond's new adversaries, at least for the next two or three films. Blofeld has subsumed Quantum and a number of other crime/espionage/terrorist groups into one syndicate - not quite the same as at point 2, above.
(4) Or, quite as likely I think, neither Quantum nor a new SPECTRE play any part in the remaining Daniel Craig Bond films, but Bond faces a villain whose activities pre-occupy him over two or three films, leading to a final showdown.
Contributors above have wondered how, assuming Blofeld is re-introduced, the "revenge" element can also be involved without a full scale OHMSS remake. I think we could use the following elements from the Fleming novels. In Bond 24, 007 is teamed with a fellow agent named, say, Gala Brand. He falls for her but she seems only friendly. Mission accomplished, save that the head villain has eluded the authorities, Bond thinks he can whisk Gala away somewhere romantic, only to be introduced to Gala's fiancé.
Then just as Gala and future husband drive off into the sunset, and Bond is leaving, a slightly sadder but wiser man, tragedy strikes. The villains have tracked Bond down, and tried to assassinate him, but end up murdering Gala and her fiancé instead.
Bond 25 - M sends Bond after our arch villain - shall we call him Shatterhand? - who is eventually tracked down to a bizarre plantation (not necessarily in Japan - other places cultivate killer plants) which is his private estate. The whole world is after him after the events of the previous story, but Bond is determined to get him. It's not out of revenge (OHMSS) nor closure (QoS) but justice. Shatterhand threatened the world but also killed two people, one who Bond worked with but one who was wholly innocent. A bit like his motivation in LTK but without the "this time it's personal" tag, because he only worked once with Gala, and his attempts at romance were brushed off. Nevertheless, he feels responsible for putting them both at risk, and wants to bring the person behind their deaths to justice.
In the final quarter of the film we learn that Shatterhand is Blofeld and like the novel You Only Live Twice, he attempts to justify his crimes. Financing terror through Le Chiffre in CR? Might it be all to the good, forcing governments to confront corrupt banking practices & money laundering that brought the world economy to the brink in 2008? The events in QoS? Again, Blofeld/Shatterhand is providing a public service, reminding the world of how precious water is. And SF? Yes he backed Raoul Silva to prove to the world how vulnerable it is to cyber-crime - how was he to know that Silva was a lunatic with a mother complex?
The final confrontation takes place, though without the end we recall from the book. Instead, for once, Bond gets the girl - whoever she might be in 25, and makes contact with M - who asks Bond to return pronto, because there's a little problem out in Jamaica that needs sorting out! 
