Nick Streak has always struggled and will continue to do so. The rest of the park should be able to cope, provided that they run the rides to a decent standard, which they have proved they can do.
Personally, I still don't think Icon is going to pull the insane crowds that people are saying. It will have nowhere near the impact of PMBO in my opinion.
This is just it though, the Streak was once the fastest queue consumer on the park. With two, 4 car trains running it saw 64 on the ride every couple of minutes. Today we have one 3 car train and a station and queue line which is among the most inefficient I have ever seen, all because they don't see fit to spend the necessary money to fix the issue.
The National also concerns me with its lengthy gaps between dispatches. That is two major rides that are below par, and both of which can do so much better.
I regard the £15 million spent on Valhalla to be the last significant investment in new hardware, since then they have lost Vikingar, Cableway, Noahs Ark, Superbowl, Trauma Towers, Wild Mouse, Black Hole, Log Flume, Monorail, Astro Swirl, Swamp Buggies, Turtle Chase, Whip, Alpine Dodgems and Space Invader. Other rides have come and gone since (Bling, Spin Doctor ect) now while some of these have been directly replaced, like the Log Flume, it's worth remembering that Infusion can't match the Log Flume in terms of capacity and the vast majority of that list haven't been replaced at all.
Couple that with the removal of the 3 train services on both the Big One and Avalanche, and the lower turnaround on just about every other coaster on park (with the possible exception of the Revolution and Blue Flyer) and I think they will be in trouble if they get busy or if Icon goes down for any length of time, especially if the Big One is down at the same time.
I don't think BPB are bragging about Icons safety any more than they did about the Big One's, just that back in 94 social media wasn't there to show that to the thousands, but anyone who bought a copy of 'where seagulls dare' will know they were proudly explaining how safe the fail safe system was (only for it to crash a matter of days later) I honestly think the are focusing and plugging the rider comfort line so much to try reverse the 'negative' effects of the Wild Mouse rather than anything to do with the Smiler.