From Yesterdays Pressrelease on 737 MAX and new 737-9 737-8 737-7

Boeing Co. (BA) is counting on the 737 MAX, the new version of the world’s most widely flown jetliner, to help capture half of a $2 trillion market in the next 20 years and fend off a challenge from Airbus SAS.
Powered by more efficient engines, the 737 MAX has already won 496 order commitments in “a very positive indicator of demand for what has been viewed as a ‘me-too’ offering,” Robert Spingarn, a New York-based Credit Suisse analyst, said yesterday in a note to clients

The new engines will be offered for the current models, the 737-700, -800 and -900, to be renamed the -7, -8 and -9.