It would be difficult because you either try to build the strongest main event you can and leave a weak undercard,or you try to match your biggest stars with the up-and-comers and spread the talent evenly in different matches,but end up having weaker main events.
Are the current talent who don't like the fact that old stars are coming back to take their spots right? It depends,current talent obviously don't draw as much as past talent,but at the same time the WWE could have spent their resources on building current stars and turn them into credible main eventers.
I think the current stars have the ability to make WrestleMania special. We obviously don't need to talk about how popular Cena,Punk and Orton are. If you count Jericho as a full-time wrestler,that easily makes 2 main events that people want to see. There are a lot of up and comers whom I like: Dolph Ziggler,Sheamus,Cody Rhodes,Zack Ryder,etc. They all look good in the ring and they're interesting. Daniel Bryan is becoming a really good heel,and he's so smarmy and self-righteous that people would want to see him get beat and lose the title,maybe even pay to see him lose the title. Big Show and Kane can be put anywhere on the card,so they can always be relied on. All these without even counting the injured stars like Rey Mysterio,Alberto Del Rio and Christian. Could they sell a million PPVs? Maybe,it'll be a stretch,but with the right booking they could.
Or you could book Cena vs. Undertaker at WrestleMania. That would surely sell a million PPVs. Add Punk vs. Bryan. Maybe Jericho vs. Orton,Sheamus vs. Big Show,Kane vs. Ryder. Throw in a ladder match for either the IC title or the US title. Surely that'll pack enough excitement for WrestleMania. It obviously won't be the best WrestleMania ever (Nothing would ever top WrestleMania 17) but I don't think it would be a disappointing PPV.