They could have used S8 to build on former recurring/guest characters, giving them more to do and bigger back stories, then near the end of the season had several of the main characters leave to pursue new careers and opportunities, whilst the newbies take over their positions.
remains onboard whilst Riker
finally gets his command. Data
would then be promoted to Commander and becomes Number One. He would be replaced at Ops by Sam Lavelle.
is requested on DS9 to help with the Klingon problem in the region, so he and Deanna
(who would be newly married) would depart to help out with the situation. They would both be replaced with new characters (a female Security Chief and a male Counsellor).
goes with Riker to serve as his XO and is replaced by a new female Chief Engineer. Though I liked her, I would love to see Crusher
depart as well and replaced by Doctor Selar, but dropping all but two characters may be a little too much.
If they wanted to, they could also resume the full-time position of Chief Conn Officer with one of the many extras who have filled the post; I'd like to see Sariel Rager back on the Bridge. Also if they really wanted to they could introduce a new Science Officer, seeing as how Data would no longer be covering the duties of Ops/Science.
TNG could then continue onwards, in the new format and they could forget all about VOY, whilst keeping DS9 looking at the darker side of the Trekverse.