The Brazilians are quite serious about an SSN, having ambitions that cover large areas of the South Atlantic where there may be oil, and have been pouring concrete in 2013-14 with the aim of cutting metal in 2015 - but firstly, on the first of four Brazilian-French SSKs. The SSN is a long way off.
The "silver bullet" quote is quite old. On the other hand, Boeing has shown through the C-17 operation how it can efficiently sustain very small numbers of large aircraft, which could point to a mixed solution: a small number of P-8As and some MSAs for non-ASW tasks.