This idea follows on from Enterprise, and the Xindi/Delphic Expanse arc. In the late 25th century, the Federation is now at peace with the Romulans, new species have joined the Federation (such as the Cardassians, Bajorans, Baku, etc.) and the Dominion has not been a threat since the war in the late 24th century. The pilot features the return of the Sphere Builders, and the crew of the ship in the series thwart threats from them, leading up to a decisive battle that the Federation wins. A sub-plot is a Dominion story, in which the Borg have started to threaten Dominion space. A Founder (it could be Odo) asks the Federation for help in defeating the Borg, but there are some in Starfleet who hope the Dominion is weakened by them, since they don't trust the Founders to abide by the Treaty of Bajor. Most of the 24th century characters may be dead by then, though Odo, Seven of Nine (due to Borg implants), or even Tuvok may be around then. There is also the possibility of doing a "Scotty" (,i.e. something similar to Relics in TNG). Say Picard was on a diplomatic mission 15 years after Nemesis, and he gets lost in an anomaly and is considered dead, only to be discovered about 100 years later.
I don't think it's implausible for the younger TNG era characters to be alive by then (having older characters like Picard be still alive would be a stretch and besides, I personally am not interested in seeing that old characters in a big role). But a new Trek series doesn't really need any appearances by them. I don't think that series would ever be made. It would be just for people who are already fans because the viewer would have to have some knowledge of the Dominion and the Xindi arc. Besides, Enterprise was cancelled. That idea would make for a good fanfic though.
The thing is, the "Sphere Builders" were nothing more than a completely undeveloped plot device. The writers of ENT even acknowledged that. There's no way a series would be created around them. Plus the fact that nobody even gives a crap about the Sphere Builders. Plus, as far as the actual shows are concerned, the Dominion and the Borg are done. The war is over for the former, and the latter have been completely wiped out thanks to future-Janeway.
my idea would be set in the time of kirk. Say a scout/destroyer class federation ship assigned to a border zone say the klingon before the Treaty of Organa. This ship would be an older type with a commander or lt.commander. A ship with a small crew so we can see a good crew break down officers/enlisted. they can get involved with pirates, klingons, out posts, some shady intelligence missions. maybe have some story lines that merge with classic trek.
Or maybe a Romulon/federation conflict. The tales of some ship or group of ships on the fringe of the federation fighting the romulon bird of prey(s). sorta like a war world II atlantic/pacific submarine against a surface destroyer(sorta like the episode Balance of Terror).
That was basically the premise of ENTERPRISE. That was basically the premise of the aborted Eric Jendressen Romulan war movie script that was rejected in favor of Star Trek '09.
Enterprise, not so much. Set anywhere between the end of the Romulan War and WNMHGB, show the Federation and Starfleet in their younger days, hopefully with a lot less upper level politics (one of the things that killed Enterprise). I was going to suggest a young Lt. Commander Kirk, with his first small command, but on reflection that would limit the character. Need someone fresh, neither Kirk nor Archer, A more Steven Decatur like character, brash - headstrong - driven, exploring the complete power vacuum surrounding the infant Federation. Except for the walled off Romulans and the rarely seen Klingons, he explores space with NO major powers. Makes first contacts (without the benefit of the prime directive), fights against minor but strong enemies, faces ethical dilemmas, gets to know his crew, this is a time of expansion for the Federation and also Earth. No one uses the phrase "empire building' but that basically what it is. It's very 15th through 18th century Earth.
So check this out- STPhoenix.com This is a new series that I subscribed to and I got a news letter: Star Trek: Phoenix is Landing at a Theatre Near You It’s here! We’re premiering Part 1 of our pilot, Cloak & Dagger, free to the public. Our thanks to these theatres and businesses for helping bring Star Trek: Phoenix to the big screen. Friday– on the cusp of Saturday, April 24; 12:30AM – Wing It Productions; 5510 University Way NE, Seattle Featuring the Wear Your Best Sci Fi Costume Contest. Best costumes as judged by Star Trek: Phoenix cast win Star Trek: Phoenix memorabilia (open seating). Sunday, April 25; Noon – Grand Illusion Cinema, 1403 NE 50th Street, Seattle Featuring Take the Family to Trek Day. Families can enjoy an afternoon at the movies and talk with cast members (open seating). Wednesday, April 28, 7-10 p.m. -- Northwest Film Forum; 1515 12th Avenue; Seattle Part of the Crack Shorts film celebration. Some of Seattle’s best show off their shorts, followed by a Q&A with the filmmakers. Sponsored by Abundant Productions (reserved seating; rsvp@abundantproductions.biz). Sunday, May 2; 5-7 p.m. – Flying Saucer Pizza; 14712 Northeast 91st Street #400; Redmond Online Premiere Party includes free raffle for Star Trek: Phoenix and Flying Saucer Pizza memorabilia (open seating). The Making of Star Trek Phoenix documentary and a Q&A session with cast and crew follow each premiere.