Deutsche's new banking analyst Matthew Wilson has slashed the broking house's  earnings forecasts for the four major banks, arguing that senior executives are ill-equipped to meet challenges from disruptors and have overreacted strategically to recent wealth management scandals.In a 50-page research report entitled "Long Business; Short Retail", Wilson has hammered profit estimates for each of the major banks over the next three years.While he has downgraded current year estimates modestly, Wilson has crunched the 2021 earnings forecasts by more than 40 per cent for CBA and Westpac.He attributes the downgrades to a combination of developing factors likely to dampen loan volumes and magnify costs."Prima facie, the outcome today appears to be - unbalanced business mix, an over-cropped consumer and an underinvested franchise which is vulnerable to economic shock, disruption, obsolescence, litigation, and regulatory/political overreach," Wilson told clients in the report."The majors are far from broken, but they have sustained a severe self-inflicted flesh wound, requiring significant cultural attention."Management must now muster the courage to change the mind-set and behaviour of boards, investors and employees in order to win back the trust of the customer."However, he also warns that the pay-off for shareholders of  customer remediation programs and internal cultural overhauls could be severely delayed if the local mortgage market implodes.Wilson views a prolonged contraction in mortgage lending as a material vulnerability of the banking system, with current mortgage books having potential to acquire "zombie status".The comparatively high exposure of CBA and Westpac to the mortgage market now represents a strategic weakness in their business profiles, Wilson asserts.He believes ANZ and NAB, which each have relatively higher exposures to business lending, are better placed to cope with lower returns from retail banking in the next three years."ANZ appears to be reading the industry trends best," Wilson said in the report."ANZ is a classic commercial bank that has always struggled to expand into the historically high return, high growth retail segment."We think it could now be entering a more supportive environment that plays to ANZ's natural franchise strengths."Although NAB has suffered extensive reputational damage as a result of evidence presented to the royal commission, Wilson believes it is the only major bank that has undertaken sufficient structural change to meet the challenge of the open banking era."The lost decade and a half appears to be closing as NAB has executed material structural change," he argues."We now have a very simple Australian and New Zealand commercial bank, on essentially one platform, nearly match fit to relish a more dynamic corporate banking setting."While the Deutsche analyst supports Westpac's decision to retain its wealth management operations, he believes it will suffer from having "too many mortgages for this part of the cycle".Looming challenges in the mortgage market are also likely to magnify pressures on Westpac's earnings because it has greater exposure to racier elements of home lending, such as interest only mortgages.CBA's huge exposure to the mortgage market means that it stands to absorb sustained earnings hits as the impact of the housing downturn contributes