Boeing B737NG order drain

Last week Boeing announced that production of the B737 will be ramped up from currently 38 copies per month to 42 next year (that was not new) and then 47 per month in 2017, when the B737MAX enters service. Boeing did not elaborate further if only MAX production will be higher from the start or if also the NG will see higher production meanwhile. But we can presume that a step of 5 more aircraft a month cannot be taken at once, so there should be a more or less gradual ramp up from 42 to 47 over a year or even more than that. That means that at least in the last year of full B737NG (before B737MAX enters service), Boeing has to sell even more B737NG's. I wonder how Boeing wants to manage this without substantial price cuts - even more substantial we are seeing today for
the narrowbodies from both Airbus and Boeing.
A timely sign that selling these extra NG frames would not that easy (and profitable) came yesterday when Southwest disclosed that they switched 20 orders for the B737-800NG to the B737MAX-8.
It may be not the last conversion from Southwest and, I am almost sure, not the last one at all. You can read here that Delta has the right to convert 40 aircraft of their order for 100 B737-900ER to the MAX model, too. And I guess most of the customers who ordered the NG in larger numbers have such rights - maybe even Ryanair.
Let's have a look at the backlog for the B737NG at the end of October - Boeing just yesterday published the numbers.
There are 1848 B737NG's in the backlog (137 -700NG, 1380 -800NG, 332 -900ER).
Then we can ad some already announced orders which are not firm yet:

Yakutia                        12
Oman Air                       5
Air China                      20
Xiamen                        40
Ruili                              14


This takes the backlog then to 1919 aircraft.
If we now “burn” the backlog down with 38 aircraft a month until June 2014 and the with 42 aircraft a month we can see that the “0” line is crossed just about when the B737MAX enters service. If we presume a gradual ramp up for the MAX and the increased production capacity fully dedicated to the MAX (which would mean that Boeing has to produce quite a lot of MAX aircraft before getting the Type Certificate and the associated risk - see B787), then we count another 700 production slots for the B737NG until the MAX takes over full production sometime in early 2020 (as I have some information about the production switch between the A320ceo and the A320neo I took the same curve for the NG/MAX switch).

B737NG backlog burndown

Of course Boeing could try to switch to full MAX production faster, but that would be a big burden for many of the suppliers. Many of them are also tied into the A320neo and have to switch production over there also.
The picture is completely different at Airbus and the switchover from the A320ceo to the A320neo. The A320ceo is overbooked already by at least 100 copies even if you subtract suspicious order from Kingfisher, United and some other smaller ones.

A320ceo backlog burndown

Increased pricing pressure for the Bombardier CSeries is a likely outcome of this. Boeing could try and "sell" airlines the B737-700NG for the cost of production which are interested in the CS300 to fill up their own slots and not to loose (further) market share.