I think this would be a mistake, which would reduce teams' incentive to maintain a strong flow of talent into and through the minor leagues. Baseball has the longest period of team control of the major sports, but this is matched by a longer time from when signing bonuses are paid until the player can make a positive MLB contribution. This is tough on the kids who don't get the big bonus, although they have a substantially lower probability of being +WAR MLB contributors. I do favor ending team control at any time after 5 years and a day of MLB service time, which would end the ability of teams to juggle MLB service time to provide close to 7 seasons of team control.
I think the answer is to provide arb after a half year of MLB service time and to peg the arb guidelines to a higher fraction of actual value produced than is used today, for each arb year. Some averaging and early year maxes might be required to prevent a player like Nola from being paid 50% of actual value for 10 WAR.
Higher minor league salaries and higher MLB minimum salaries are also warranted. Both could be doubled -- more than doubled for the low minors.
It is also worth doing away with QOs and teams losing draft picks for signing any FA. A system like football's, where a certain number of comp picks are available based on the net FA player value lost during the prior off-season. Except for losing a star, such as Harper, the top pick might be start of 3rd round, while a star would grant the team an end of first round added draft pick. (Again, just player examples, if you lose a Harper and sign a Machado, you get nothing.)