Well, you didn't say both 2nds. You said 3 1st's and a 2nd
All the same. I think that Carolina would wilt at upping the ante into the second round (unless the bid also includes less value in future years) because their team is not as talented as San Fran's was when they traded for Lance. San Fran was trading from outside the top-10, and I think the impression was that future first rounders from them would easily be far later in the draft. Carolina might not be looking at that kind of timeline, and I dont think anyone is under the impression that Carolina is as competitive in this upcoming season as San Fran is with Lance on the bench or injured.
It isnt an unreasonable bid (so if this trade does happen, I will be doing backflips) but I would think the more valuable the haul in this year's draft, the less likely Carolina is willing to trade away higher picks in future years.