Sales of Nintendo's Switch gaming console may have peaked. On Thursday (May 6) the Japanese firm forecast shipments of 25.5 million units over the current business year. That would be down on last year, when Nintendo was a big winner from the lockdown-driven gaming boom. Its operating profit jumped 82% over the year to $5.9 billion. But the Switch has now been on sale for five years, and there's growing speculation over a hardware refresh. Each generation of games console typically lasts about seven years before being replaced. Nintendo shares have soared around 90% since March last year, as fans flocked to games like "Animal Crossing".Sales should get fresh support from upcoming games including a new Super Mario title. But the stock is now down around 10% from this year's highs, as investors look ahead to the Switch's peak and replacement. Some also worry that the firm is overly dependent on consoles, with its expansion into mobile phone gaming seen to have stalled. Rivals Sony and Microsoft have more diversified offerings in the games market.On Thursday Nintendo also warned that a global chip shortage was affecting production, adding to uncertainty over its outlook.