Possible Cole's character re-invention in S5
Instead of demolishing Cole’s character and binding him to Phoebe until the end, on a delusional level of "the one and only love" train, I would love to see him fully embrace + explore his human side, by actually MOVING ON and distancing himself from Phoebe, as he initially planned when he packed his cases when Paige came and stopped him.
Maybe also rediscover his human feelings - empathy, sympathy, attraction, need to care, desire for another human being, awakened by Phoebe in S3, fall for another non-Halliwell witch or ordinary woman.
Not to mention that it’d be fun as hell to see Phoebe/Alyssa ego bruised, aka « but I thought I'm the only one allowed to move on from our marriage !!! » reaction when she would accidentally discovered him with another woman. And maybe chase be jealous / chase him back for a short time :>
And even if not, that would give a much healthier idea to the audience.
The idea that wrong timing, wrong choices made, wrong words said, can lead to breaking even the most perfect match made in heaven (or hell for that matter).
That 2 adults can learn from their mistakes they've made, acknowledging them, as well as the harm and pain they caused to each other, so they will treat their next partner better.
And by rediscovering and redefining themselves separately, apart from each other as a couple, they could come back together stronger and for good in S8, than the first time round in S3-S5.
Much interesting, with-some-meat-on-bones storyline than "Imma jump on every duck coming my way" Phoebe coping with her divorce or never ending Piper/Leo drama for 8 seasons.