I absolutely think that Marner and Nylander will be better players next season than Hoffman, especially if Hoffman becomes a Blue and is asked to play RW. I think they will very likely be better players than Wayne Simmons next year, although Simmons is a much better fit on the Blues than Hoffman IMO. Both Nylander/Marner fit the speed/skill identity we appear to be crafting better than Hoffman/Simmonds.
You're only talking about one half of the equation. Any gain on the forward end is likely going to be mitigated by the downgrade on the defensive end...unless you think replacing someone of Parayko's ability (who, for my money, is our second best all-around defenseman) is a given? It shouldn't be. I can pretty much guarantee you that Parayko is also a better fit for how the Blues want to play than anyone they might be able to replace him with.
We know borderline 1st line wingers are available, and we see players like that change teams relatively often. What borderline RH #1 defensemen are available? How often do those players get moved? That part of this discussion is being left conveniently abstract. Armstrong isn't going to need concrete options, not abstractions.
I don't trust any of our prospects to consistently match Nylander or Marner over the next 5 years. I think they can match the 'low hanging fruit' guys you are talking about in that window at a controlled cost, but if that's all they do, then we will need to supplement them with more guys from outside the organization. If we just get a stop gap solution now, I firmly believe we will either need to overpay that stop gap for declining production for years 3-6 or spend more assets to bring in more low hanging fruit.
Why do they need to match Nylander/Marner? Are you saying adding a couple of 20 goal/50 point guys isn't enough to make this team a contender? I disagree with that premise. Why would the Blues need to extend the stopgap solution or bring in another for years 3-6 if a couple of our prospects reach that (very reachable) level after a couple of years? And how would adding Nylander (currently a 20 goal, 60 point guy) instead of a 20 goal/50 point stopgap somehow mitigate that future need entirely? That doesn't make any sense to me. There isn't a massive impact gap between those players.
I believe that there is serious merit to trading Parayko to plug that hole with 'high hanging fruit' than spending two to three 1sts plus two or three prospects to repeatedly plug that same hole in 2 year increments with low hanging fruit. Especially since a lot of the low hanging fruit rumored to be available this summer still leaves us with no right hand shot in the top 6 or presumptive PP units.
I'm not sure I love Parayko for Nylander straight up. I'd do Parayko for Marner straight up in a heartbeat, but I'd probably need the Leafs to either add slightly to Nylander in some way (I think it would need to be a package where both teams are sending 2+ assets and some short-term bad money going Toronto's way). My point is that Parayko shouldn't be off the table for Nylander discussions.
Now you're assuming that the hole at RHD won't become an asset sink that won't require an overpay or repeated plugging. This is a curious assumption given that we actually have fast, talented, promising internal RH forward prospects for the center and RW positions, but we have absolutely nothing that comes close to filling the hole you're willing to open on the defense. Also, there's also nobody except for Carlson, who is going to absolutely paid, that could fill that hole available in UFA. A trade is the Blues only recourse, so where is this potential defenseman coming from? I can't think of anyone who has quality RHD to spare, much less one that is young enough, cheap enough, and under team control long enough to be considered a viable long-term patch for the hole.
I think BlueDream hit the nail on the head when he said it's all about finding the path of least resistance, because the asset cost will be there either way if you're looking for high quality pieces or long-term solutions. What's the point of mapping out half the plan (Parayko for X) if the other half is completely speculative and unlikely to materialize? Especially if there's no internal backup plan, either short or long term?
The straightforward solution is to plug the top 6 holes by getting the best forwards you can get for the assets you consider to be expendable (i.e. not current fixtures in your competitive roster, and not prospects you absolutely need to hang onto). We can ultimately agree to disagree about the viability of our hypothetical discussion of alternate paths, but in real life I think the straightforward solution is the one that Armstrong will ultimately pursue. I would be absolutely shocked if Armstrong traded Parayko to address his concerns at forward this offseason.