Kyle Busch's teammate Austin Dillon won at Richmond Raceway, and the result was a severe hit to the prospects of several drivers on the playoff bubble. The playoff cutline prior to the win was, to some degree, stable at that point, with drivers such as Chris Buescher having a healthy points lead over the bubble and Tyler Reddick carrying healthy points numbers.Nevertheless, Dillon's surprise victory as the 14th different race winner of the season immediately guaranteed him a place in the playoff. This victory ruined the hopes of some of the drivers who were earlier hopeful of securing a place in the playoffs on the basis of points.What is also notable is that Tyler Reddick, someone with a cushy margin and in fantastic form, lost almost 30 points to Alex Bowman at Richmond, which put him only one spot above the playoff bubble. Bowman, who was second behind Dillon, was on the playoff bubble, and in order to get himself in, he will need a major points haul in the final regular season race at Daytona.Here are three more Cup Series drivers whose playoff hopes hang in the balance, including Kyle Busch.1. Kyle BuschKyle Busch - Source: ImagnKyle Busch has had a difficult season, though he has shown fragments of good performance. Despite some promising results, there have been plenty of setbacks and the two-time Cup Series winner finds himself in a precarious position going into the final regular season race.Busch's year has been one of mixed fortunes. Although he is in 19th place in points standings and 148 playoff points behind the cutoff, his only way of finding his way to the playoffs is by winning at Daytona.Kyle Busch has a strong record at Daytona, though, and will hope to roll back the years on Saturday (August 23). But based on his season so far, it could be too uphill a mountain to climb for the veteran.2. Chris BuescherChris Buescher (17) waves after being introduced to fans before the start of the NASCAR Toyota / Save Mart 360 at Sonoma Raceway. - Source: ImagnChris Buescher is on the bubble going into the final race of the season. He has already had a number of standout performances with the victories in Stage 1 and third-place finish at Watkins Glen, leaving him with a cushion beyond the cutline to the playoffs.Buescher has been fast and competitive and has had several top-10 finishes this season. He came close to victory at Michigan and Darlington, showing his capabilities.The RFK Racing driver finds himself 60 points shy of Alex Bowman, who currently holds the 16th spot. He will realistically need a win at Daytona to qualify, which could prove to be tricky considering his average finish of 18.8 at the track.3. Ryan PreeceRyan Preece (60) looks on prior to the Go Bowling at The Glen at Watkins Glen International - Source: ImagnMuch like his RFK Racing teammate, Ryan Preece finds himself so close yet so far going into the final regular season race. Preece has performed well enough to be in a position to possibly qualify for the playoffs. One of the successes was the pole that he earned at the Richmond Raceway, the second pole in his career.Going into the season finale at Daytona, Preece finds himself 94 points shy of Bowman and needs a win to make it through.