Op here -- great info -- thank you all for responding.
Couple points for clarification for questions asked --
Mother is 5ft and Dad is 6ft... so...

He's average right now for his age.
This year, as U10, he's done an exclusive GK training 1x a week, Team training 1x a week, and an academy across all of the U10 teams where it's been a mix of both for him. The other GK that plays on his team currently rarely if ever goes to the separate GK training so he's been kinda it.
He LOVES goalie - watches videos of soccer constantly - thinks about lines ups for his team - runs around inside and outside with a ball - thinks of himself as a goalie first... but he's not totally sure he wants to ONLY play goalie on a team. He loved getting to take a free kick last weekend (which he totally nailed -- right over the heads of the "wall" and into the goal). He scored twice in his previous game too - playing midfield.
Evidently, the GK coach is recommending him to go to the highest team level BUT there is a new kid that hasn't played at all with them that he thinks is also very good -- so there is talk of having them "compete" for the spot and maybe some kind of rotation. So, we've talked to him that all of his hard work and extra practice has been noticed...but sometimes, there just comes along another player who is better. That's that.
In terms of being booted from GK and then what.... He swims competitively and knows that sometimes it's your year and sometimes not (he was all-stars at 8 but this summer will swim 9-10 so will be at the "bottom" - we have good 10 year olds and he knows he may not even make A meets this year after being literally the top swimmer in every stroke as an 8 year old).
Thanks for all of the input -- we are still waiting on his invitation for which travel team he will be on in the fall -- I'd love to see him get the top team to show he's been recognized...but I think the next team down has more of a chance of being competitive (and maybe winning) so would be totally fine with a bid there too!