I think you've got this the wrong way around.
Move him on and bring in 2 players who are greater than the benefit of keeping him.
This is the right idea.
Again, in normal circumstances. Our squad is diabolical, as a result of recruitment that is beyond shocking. We will be fighting relegation again. The teams that went down all had average or poor GKs - same as last year. People underestimate the difference a good GK makes at the business ends of the table. You can only really get away with average GKs if you are a comfortable mid-table team. Even if we have better recruitment than usual this summer, there is no guarantee that will be the case for us. Would be mad to move Pickford on in our current state.
Generally I agree with you - we've had enough conversations to that effect on here - I want young talent acquired from across the world. But part of realising where we are should not be getting in established players who are 26 plus (something I'm sure Dyche will be pushing for), but rather, trying to keep hold of the few good players we have.
In Pickford's case, if he has another good season, he will still have suitors next summer. If we have gone some way to sorting out the rest of the squad and have finished comfortably in mid-table, we could look to move him on and invest then. If we sell him and look to get a really good GK to replace him this summer, a huge chunk of the cash generated would have to go on his replacement. What's the point?