1) I didn't consider Canada a medal contender because their individual times weren't really good this season. You could say the same about Italy (or Japan/China in the past), so it probably wouldn't have been a shock to see Canada winning a medal. I considered the US, Jamaica and GB the clear favorites, but i guess in the 4 x 100 m relay you shouldn't count on none of the favorites dropping the baton.
2) You are right about Dunfee's medal record in the 20 km event, but i thought that the removal of the 50 km event from the olympic program would lead him to focus more on the 20 km event and becoming better there.
3) I considered the US, Jamaica, the Netherlands, GB and maybe Poland to be (clearly) better in the women's 4 x 400 m relay, but you can't deny the canadian track record. Canada might become the new Poland in this event, based on their individual times they probably shouldn't be as fast as they are, but somehow they are still always in the fight for the medals, which is even more surprising when you take into consideration that changeovers are less crucial in the longer relay.
4) I would honestly shocked if Mayer would win a medal next year. I probably wouldn't even bet on him fininshing the competition. Not even sure if he will qualify (he will have to finish a decathlon before Paris to qualify). For me LePage is probably the biggest favorite ahead of Neugebauer. I would rank the favorites for bronze as follows: Warner (age), Skottheim, Rooth, Garland, Tilga, Victor (age)
I have a lot of trust in the norwegian program. Both of the norwegians focused on the european U23 championships this year, which explains their performance in Budapest. Not sure how likely Moloney is to return at 100 %. I think he hasn't done anything the past 2 years. Neugebauer has horrible technique in multiple events (high jump, pole vault) and is quite heavy, so he might be the most injury prone out of all of them. On the other hand he has a lot of room for improvement if he ever fixes his technique. He could probably gain 100 points alone in high jump and pole vault. Neugebauer might have the problem (unlike LePage and Warner) that he still has to qualify. Germany has multiple guys who could achieve the standard next year, so he will probably have to score higher than them to qualify.
5) The only potential new canadian medal contender (someone who hasn't won a medal before) for me is Sutherland in women's 400 m hurdles, but even for her it will be difficult, given that Bol and McLaughlin seem like locks for 2 of the 3 available medals. Newman in women's pole vault is probably too old to have another big improvement. Anyone else turning into a medal contender would be a shock to me. Of course it doesn't help that athletes like Nettey, Barber or Debues-Stafford flamed out rather quickly.