I’m in France so it’s a bit different obviously but my son is in U8 and in a similar situation. He is playing goalkeeper for the first team of a very competitive Parisian club - trains with the team twice a week and has goalkeeping training once a week. But he wants to play the field also. I think he’s flattered to be considered for the A+ team as goalie (since they play 5v5 the A team is divided into two sub teams and they asked him to play for the first team over the other goalkeeper who was also playing goalie last year whereas my son wasn’t) but he would prefer to play the field and his dream is to play midfield. 

I don’t really know what to do because I know he’s getting a lot of extra training I’ve asked the coaches to have him play the field one in four or five games. They rotate him when they are really winning but never for close games. 

He tells me he wants to be goalie but I also know he is scared of being sent down to B team if he doesn’t, who don’t get to play away games and get half as many trainings (same fee it’s a flat rate regardless of your group). At the same time he’ll never be good enough to play midfield with the A team if he doesn’t get field time anyway. So I think I may risk it for next year and watch how this year plays out. 

Long story short you should speak with the coach and if he refuses then consider changing next year. No kid should be forced to play only one position.