2. A 'Time Crash' Moment
Anything the Fifth and Tenth Doctors can do, the Second and Eleventh should at least get the chance to replicate. They do briefly in ' Shadow Of Death' and it serves as a mouthwatering prelude. It could have happened at the end of 'Cold War' such was Mark Gatiss's intent to give the Eleventh Doctor more in common with his younger self than just a bow tie and initial love of hats but sadly didn't. It could even be built into the Season 6B theory,with the Second working for the Celestial Intervention Agency and needing the older incarnation's help at the end of separate adventures in their own timelines. Whether or not 'The Two' or 'Three/Five Doctors' would have occurred for the younger man, or 'The Day Of The Doctor' for the senior, wouldn't necessarily matter. A number of alternative televisual angles could also have been opened. What if the Eleventh had attempted to save the Second from his fate at the end of 'The War Games'? It could have left the door open for future meetings between the two whether or not the plan had a satisfying pay-off. Not to mention set the scene for future meetings with the Third Doctor,who may or may not be pleased to see him. They may have the Silurians in common, but anything else...