Welcome back old friend.
First of all, Elway has scouted QBs with Peyton the same way he did when Tebow was at the helm. He is always looking for QBs to develop, look at this year's team. Osweiler and Dysert. Dysert really has no business on the team, but Elway wants to continue to develop these guys. With Tebow it likely would have been accelerated, but John is on the record that Tebow would be given every opportunity to win the job.
You could take that as they were looking for someone to replace Tebow, which they very well could have been and it's probably true, but nothing has changed year over year as to how they operate in looking for QBs.
So it is likely that Elway would have drafted a QB higher if Manning didn't come our way. We would have taken Weeden, to bring competition to Tebow. As Tebow is a horrible practice player, Weeden likely would have beaten him out, much like Orton. We all know that Tebow shines in game situations, so yes it would have been an easy way out for Elway to replace him. If Tebow would have bundled together some stinkers in the next season, they could have easily justified replacing him.
That didn't happen though. Manning was on the free market, he came to Denver, draft plans changed accordingly, Tebow was traded, life goes on. Football.
Furthermore, I find it odd that this comes as a surprise. Tebow had a lot working against him. First, he was not an Elway draft pick. When executives get shuffled around at the top, they want their guy running the most important position on the team. Second, while he had a wonderful game against the Steelers, he turned in a poor performance in NE. Third, you have to take a gamble on Peyton if he's out there. Lastly, he had plenty of contract incentives that kicked in. If you want to move on, then there is no reason to allow the guy to continue to gobble up money that could be used elsewhere.
Even with that all said, Elway embraced the moment and celebrated the win. Gears may have been turning behind the scenes, but he can't just sit there and pout that it's working against what he wants to do long term. If anything he was riding the hot hand and letting things play out.