I don't know how good or bad Lance will be. Shanahan is great with scheming receivers open. And they seem to do very well with the shorter, safer passes when he wants to protect his quarterback from himself. But if Lance doesn't work out, it could set them back for a while.
I know people can say we gave up those firsts for Goff, he didn't work out and we're still sitting pretty good as a team. But Goff did have two really good seasons leading a top tier offense. So its not like he turned out to be a bust. We won quite a bit with him. Time will tell if Lance can win a lot of games for them.
If they didn't give up those future firsts for him, I have to wonder if dangling those picks would be tempting for the Packers to trade Rogers to the 49ers. Right now, I'm pretty glad they gave up the resources needed to trade for a proven talent. Now they have an unknown talent.