There are many players and parents who need help getting an honest evaluation from a neutral qualified source. There is certainly a need and a market and properly culled ex-scouts would certainly qualify.
However, I don't agree that the premise is to keep players playing the game. Let's call a spade a spade. If they have made it to 13, 14, 15 and have a skill set that gives them a chance at college ball or beyond, they don't need to be talked into continuing play, they need to be given that assessment so that they know what realistic college level to target based on their tools and projections. Yeah, a plan is fine but they typically know what their strengths and weaknesses are, they just need to know where their likely fit is.
There is certainly a fair supply of qualified individuals (combined with resources like HSBBW) that would be willing to provide that assessment at little or no cost. There is also a fair supply of training facilities that would do the same for a nominal cost, far less than the likely $500-$750 we're talking about here.
That said, if a parent doesn't want to do a little leg work and/or feels this route would be the best bet for a truly qualified assessment, and they have the extra money, then go for it.
I understand the idea of attending the games but if a decent local instructor did a short on-field evaluation and asked a few coaches about the kid's game make-up, much of the same conclusions will be drawn almost every time. Those local guys are often willing to attend a game or two as well and, in fact, probably have already seen the kid play.
It always blows me away how many parents are willing to spend thousands when they can utilize resources like HSBBW and learn to target their plan so that they can save a huge portion of those thousands - FOR FREE, yet they just won't take the time to do that.
I guess if you have it and want to spend it that way, who am I to say otherwise. On the surface, I have no problem with 4seamer's model. I can, however, imagine some interesting parent-group-at-game discussion when they find out that Jimmy 13U's dad is paying a pro scout to personally follow and assess him. 