SBL sent out a newsletter on Monday which contained some information about the forthcoming revamp of the Nestle-Aland critical Greek New Testament, known as NA28. Here's what they had to say:
Following intensive preparatory work, the new edition of the Novum Testamentum Graece ("Nestle-Aland") has been published by the German Bible Society. Thus this standard and globally preeminent reference among Greek New Testament editions is available in a fundamentally revised and improved edition. One focus of the revision was on the critical apparatus whose structure was simplified. For instance, the combination of variants using "sed" or "et" and the distinction between consistently cited witnesses of the first and second order have now been removed. In addition, the readings of the newly discovered Papyri 117–127 are listed for the first time, opening up interesting perspectives particularly for the Acts of the Apostles. In the Catholic Epistles, this edition has been made consistent with the "Editio Critica Maior". This led to more than 30 modifications in the main text and resulted in a critical apparatus that is newly compiled in its entirety for this section and includes a new selection of witnesses and variants. The cross-references in the margin were also systematically revised and supplemented mainly with references to early Jewish literature.
They also announced a special session at the SBL Annual Meeting in Chicago where the editors will explain the principles of the revision and present a digital edition. This special session will be Monday 19th, 1:00 pm - 2:30 pm, room W194b - McCormick Place.