I think Canada will definitely split pairs. Pretty much any country with medal contenders in pairs will do so. D&R's SB LP score is only 1 point ahead of Stolbova/Klimov (who I assume will skate the segment for Russia), so they are not really guaranteed to win the LP segment either and it would be a waste of resources for them to go and possibly finish 2nd which S&B or MT&M could have done anyway. D&R are also older and Eric had that hip flareup last year.
Most are assuming Chan will do both and I think he very well might but to be fair, Messing's LP SB is 10 points higher than Chan so subbing here would not be crazy (granted Chan's SC performance may have been an aberration). If Chan were considered an individual medal contender, I think they would split. As of right I don't really know where his head is it, if he is trying to just hang in there to do the team event or if he really wants to add back content and fight for a medal. I mean, yes, it sounds weird to use Messing and S&B rather than World medalists W&P and Daleman, but IMO it should be about strategy, not who's going to given a medal.
V&M I believe have already expressed a willingness to do both segments, and we saw in Sochi that it didn't affect their skating in the individual (actually they struggled a bit in the team event and were clean in the individual). W&P could win the FD, but V&M are virtually guaranteed to do so if France doesn't make the cut, so really, there's no scenario where W&P can improve the team's overall chances, only hurt them. Russia won by 10 points in Sochi but this time I think it will be closer, looking like a Canada win by 2-3 points but could certainly tilt Russia's way, so they really cannot afford to lose placements here and there especially with Chan being so erratic this season.
Ladies split will depend on what they do with men and I think Daleman's win helps her. It doesn't guarantee anything (Sotnikova was Russian champion in 2014 and wasn't picked) especially since Osmond is the clear leader internationally, but I think the Canadian sensibility would be to not exclude their national champ. Mistakes here notwithstanding, Osmond is a clear choice for the SP, the only one who could challenge Medvedeva if she's not clean. I personally would go with Osmond for the free as well, as she has a 16-point higher SB, plus she has a much bigger PCS and GOE cushion if she makes mistakes. Looking at the National scores, Daleman had to skate a 7-triple program to beat a flawed Osmond in the free, so Daleman needs to go clean to score like Osmond with mistakes, but Daleman has been inconsistent this season, so it's not worth using her if she doesn't go clean as she is more likely to lose to Italy, Japan, or the US.