'Will X ever do Y?'
Standard, and ONLY answer: 'If they feel like it, and can afford it.'
You expect folks to guess? The military as a whole is tending towards digital, and trunked, so yes, it's likely that 'someday' they will go to those. That's the most that can be said, unless you have 'inside' info.
I can easily say that 'eventually', they, and every other agency of all types, (except maybe aircraft) will be using radios which no current scanner can monitor. Why? Because standards change. APCO-25 is monitorable. The followon to APCO-25 'splits' each channel into two, using multiplexing. Your scanner can't receive it. This is the way technology works, over time. This will be especially true now that communications is going 'digital', as that allows all sorts of error correction, multiplexing, and other stuff to be added to new standards. Only the desire to keep radios workable with other agencies keeps things rounded up into 'standards' that may possibly be scannable.