Answer:
Most likely, the Continental Army would have been defeated had it not been for French, and to a lesser extent Spanish, aid during the American Revolutionary War.
During the 18th century, the British Army was one of the strongest in the world, along with the French and the Spanish. Therefore, French aid on the battlefield was essential to equalize forces and experience between both sides. In addition, the French and the Spanish carried out maritime blockade operations that were essential to prevent the resupply of British troops in America.
For these reasons, without foreign aid the patriots would most likely have been defeated.