hey, if you climbed to 5897 and had no problems, you can cover Elbrus and Kili, no problem. having said that, every trip is different and altitude sickness can strike any time, even the same mountain that you have already climbed! (just never take anything for granted) Denali is doable, but there are so many factors / obstacles that can stop you.
Here are the considerations: (Your) Knowledge, Skills, Experience, Training, Proper Gear, Health, Weather, and the last kicker is Mental Fortitude. The mental part will get you up the last few thousand feet (1,000 meters).
One mountain at a time! (okay, with one in sight after the next one).