Whilst I am not disagreeing with much of what you say, I cannot see him signing a 10 year deal with us. I think the longest contract ever signed was Messi signing for 9 years. There may be others, I am not sure.
But either way, the lad may want to come to City - I certainly hope he does - but we have to be realistic and understand that we are not the darling club that everyone wants to play for forever. We have the bluest of blue tinted specs on. Players are always interested in playing for Real or Barca or Bayern, or (dare I say it) United. I cannot see a 20 year old agreeing to tie his entire prime footballing years to us, straight off. I think it will be a 5 year deal, if we get him.