As Christmas approaches and pester-power reaches a crescendo, the stores are desperately trying to lay their hands on this year's must-have accessory – the new PlayStation.

The console has the computing power of a small mainframe, the graphics capability of an IMAX film and a sound system to rival the new Birmingham Symphony Hall. But most importantly, PlayStation 2 has a brand name to die for and a marketing push set to dazzle as it is launched across TV screens and billboards this week.

Sony hardly needs to advertise. Demand is already outstripping supply and the word 'PlayStation' has its own presence and power outreaching any marketing slogan or catchline the company has ever created.

But Sony faced a dilemma with the launch of the PlayStation 2 – what to do with the PlayStation?

Sony has redesigned the console – now the PS One – making its case and its name smaller and now the company's marketing team has decided to reposition the product as an entry-level machine aimed at young gameplayers and women – the company believes there is life (read sales) in the old dog yet.

Any company that has had a successful product knows that there comes a time when difficult decisions have to be made – whether to retire it, let it die naturally or reposition it. The same is true of industries which have established a clear position with a particular service and which, when they update their offering, have to decide how to market the new and the old.

Law firms which have just begun the process of packaging their skills and work as products or services positioned and sold to clients who form a strong relationship with that particular product and its brand, face a similar dilemma.

They might have created a coherent M&A service package or an innovative virtual dealing room product, but when legal skills or technology allow them to innovate that offering they will face the problem Sony had with the PlayStation.

It was not a redundant product. In many ways it was still superior to its rivals. It had a market position and a price point that offered clear commercial potential. Furthermore, it had a loyal following and status within the gaming community, many of whom were not in the market to upgrade.

Firms that have made significant investments in upgrading their human skills or technological infrastructure will rightly want to make a noise about their new offering and develop its customer base but they would be foolish to lose the brand loyalty and customers that the old product furnishes.

Sony spotted that with some repackaging, cosmetic surgery and marketing it could retain loyalty, ensure existing customers did not feel that they had been abandoned or even betrayed, and pull in a new customer base.

Of course this may be a case of Sony's techie whizzes leaving the company and the marketing chaps desperately trying to catch up and rescue what they could from built-in obsolescence.

Even so, we have a lot to learn from a business that with a simple lateral leap has enabled itself to strengthen existing relationships and open up new ones simply by remembering that customers and products have relationships that cannot, and should not, be wiped out by new advances.