How many Welsh U20's WC players will be considered for the 7's team?

As the title states, how many of the promising players (in a disappointing campaign) will get a chance with the next Wales 7's team?

I feel that for the more outstanding players within the U20's squad, the 7's would be the perfect environment to hone their skills and emphasis the importance of basic skills and playing 'heads up rugby'. This could then make them really exciting when they return to their respective regions.