Here in the printer’s manuscript, Oliver Cowdery initially wrote will (the normal modal verb in modern English for expressing the future), then he corrected it to shall. The change occurs with the same level of ink flow, so this correction appears to be virtually immediate. In the surrounding verses (from verses 6 through 24) we have the following sequence of modal shall ’s and will ’s (the reading here in 2 Nephi 27:15 is marked by an arrow):
| verses 6–11 | 17 shall ’s |
| verse 11 | 1 will |
| verses 12–13 | 7 shall ’s |
| verse 14 | 2 will ’s |
| verse 15 | 3 shall ’s |
| → verse 15 | will > shall |
| verse 15–16 | 2 will ’s |
| verses 17–19 | 3 shall ’s |
| verse 19 | 1 will |
| verses 19–20 | 4 shall ’s, 1 shalt |
| verse 21 | 2 will ’s |
| verse 22 | 1 shall, 1 shalt |
| verse 23 | 1 will |
| verse 24 | 4 shall ’s |
Since either shall or will is possible (especially given the surrounding variation), Oliver Cowdery was probably correcting 𝓟 to the reading in 𝓞 when he changed will to shall in verse 15. The source for the will may have been the following will in “and I will read them”.
Summary: Retain Oliver Cowdery’s corrected shall in 2 Nephi 27:15 (“and the learned shall say”).