That's a difficult question because there is just so much that goes into winning ONE Stanley Cup. Much less multiple. No small amount of luck, too.
After Crosby was drafted I think fans had a pretty good notion that a core consisting of Crosby, Malkin, MAF and whatever they had pulled from their previous drafts (Whitney, Orpik etc... Letang was still a complete unknown and hadn't blown training camp up yet) should compete for SOMETHING. By the time 08 had rolled around though Crosby, Malkin and Letang had established themselves as legit and were coming off a SCF with Detroit. Everyone had gotten a good eyefull, in other words.
If you had asked me from the point of drafting what expectations were... I mean... reasonable. You are happy to achieve ONE Stanley Cup. It is the most difficult prize in sport, IMO. But after seeing those guys and what they were capable of? Don't mistake me... I'm thankful for 3. But that's also appropriate for their level. This is an exceptional core. I personally think they've left one on the table or at least a couple SCF appearances. As exceptional as the core was... it still needed served in order to maximize what they could do. And for many years the FO and coach did not.
And falling into old bad habits is evidently easy.