Morelos will rightly earn us a substantial return on our investment in him - he's a good striker who is still developing towards his potential.
But we're setting ourselves up for disappointment if we think it'll be a £20 million fee, or even half that, without him demonstrating a few things to potential suitors. Chiefly, playing well over a decent number of games against quality opposition, and demonstrating that he has the brains to go with his obvious skill & power.
More encouraging is that we seem to be on the right track. Buying rough diamonds & polishing them up has to be our approach - the days of off-the-peg quality will not be back for a few seasons at least. When eventually we do part with him (I'd accept £8m right now, hopefully more in a year), we must ensure that his replacement(s) are already scouted & ready to sign.