It seems likely that we can see that the premise of a discussion everyone being on the same page is a bit off base, and the foundation of bitcoin's set up or governance is not really needing folks to be on the same page.. , so if they are not largely on the same page, then the status quo continues.. and if there are enough of them on the same page seg wit goes forward and if there are enough of them that believe that a blocksize limit increase is a good idea, then that goes forward.  It can take a long time to play out to get from discussion of a topic, creation of code, testing and vetting the code and then getting a considerable amount of agreement (consensus level) on it's activation.

Surely, seg wit is much further along the road towards consensus than any blocksize limit increase... and sure, there could be simultaneous proposals or seg wit could get pulled and revised if that course of action seems more likely to achieve consensus.. but at the moment seg wit is on the table, and those who are working towards blocking it don't have feasible code that has gone through the vetting process.  It is pie in the sky to work on a premise that all folks are going to substantially agree - but it is not pie in the sky to recognize that some proposals are further along in the process and have better chances to survive than others.  Even though there are a lot of naysayers regarding seg wit, seg wit seems to have really decent chances of getting activated in the year's time that it is on the table (or alternatively some close version with agreeable tweaks). 

It would not be the end of the world or even close to the end of the world if bitcoin does not achieve consensus on any of the proposed changes in the coming years.  Bitcoin is still going to serve quite well, even though getting closer and closer to activating seg wit would probably be very bullish for bitcoin's prices, because it seems to be a very good next step....