I believe Metcalfe’s Law is already long disconnected.
The curves look good so far but I think it is rather arbitrarily chosen to do so without necessarily reflecting the fundamentals. If Metcalfe’s linear parameters were instead chosen to closely fit the early phase (first 3-400 days from 17Jul2010), one can see the predicted price values for 2013-2014 would fall well above of what they are currently drawn, hence my introductory statement.

My best guess is that Metcalfe’s Law was holding true and was suppose to give accurate predictions in a bitcoin-world of independent miners (&users). On contrarily, the vast majority of today miners gather around pools that I suppose can be regarded as ‘super-nodes’, where all miners hiding behind them are perceived by the outside bitcoin network as Neffective=k*Nreal, where k<1. In effect, Nreal is reduced to Neffective and similarly the number of transaction is reduced too (since most pools pay above a certain threshold instead of paying at each block found). Alike, many bitcoin users/traders (including those who are not necessarily miners) hide behind exchanges that act as super-nodes too.
If one assumes k=1 in early days, it would be interesting to see the curve broken in two parts (or three parts – I can see more than one inflexion points) and from there to firstly compute the proportional coefficient(s) for best fit on sqr(N) while k=1, then to use the same coefficients for computing k for later/present times.
By further including a k=f(t) in the model it may open it for exciting correlations and perspectives.

In the above I fully agree k would be the coefficient for small-world effect and k=f(t) would model the world getting smaller (from bitcoin viewpoint). Maybe instead of abandoning Metcalfe’s model altogether one may try to k-adjust it so as to correlate the price with transaction volume/ no. of addresses, which are imho very good input parameters.
So, in essence, my proposal would be to consider Metcalfe's adjusted model as a second tool to predict price variation and eventually to increase confidence in the logistic model during times when price under-perform instead of repeatedly questioning the validity of initial assumptions.
Please comment/criticize.

I’d take this opportunity to thanks for the great work done and published here! I think this is one of the best if not the best thread of the entire forum. Very clean, accurate and at high standards – my sincere congratulations! Great contributors too!
With your permission I will have some questions on the subject/logistic model but I’ll take some more time to go again through it.

Best regards,