I don't really follow the international scene too closely, but apparently these two are pretty impressive players, and a politically big deal in Cuba. Their father was also a star player in Cuba, so they are basically Cuba's baseball royal family.
The older brother has apparently always been viewed as critical of the players who defect and chase American money, so this will certainly be viewed as an indictment of the current situation of Cuban ball players, if one of "their" guys finally throws in the towel. Experts are also taking this as a clear sign that negotiations between MLB, the US Government and Cuba to allow MLB teams to negotiate directly with the Cuban Baseball Federation at worst have broken down and at best are going nowhere, as the Gurriel family would definitely have a finger on the political pulse, and the brothers wouldn't have pulled the trigger if they thought any other options would become available soon.

Interestingly, it appears the current situation is working against both of them. Though the older brother is tearing it up in the Cuban leagues (a .500 average is insane, no matter the level!), at 32, he's getting old enough that most teams wouldn't be willing to drop mega-deal money on an unproven talent at the highest level.

Meanwhile, the younger brother, who is widely viewed as international baseball's biggest prospect, won't turn 23 until October, BUT, that also means he's subject to MLB's international signing restrictions - which aren't lifted until a player is 23 - so the majority of teams who'd be interested and have pocketbooks large enough to make a big deal, would also shy away from a big deal since most of these teams are at or past their international signing limits, and the penalty they'd pay would be close to as much as the contract itself. Talk about two guys in limbo.

Will be interesting to see how it plays out.