The idea of clubs having to sell their homegrown stars to bank pure profit amid the Premier League's tightening Profit and Sustainability rules [PSR] sums up exactly what is wrong with modern football. Clubs have been forced to cash in on stars they have matured and nurtured in recent years to remain within the PSR boundaries. Manchester United had to sell Scott McTominay last summer when former manager Erik ten Hag was against the idea. McTominay was a player that often divided opinion among supporters, with some recognising his value to the squad and others glad to see the back of him. Ahead of this summer's transfer window, you would be hard-pressed to find any United fan that wants to say farewell to Kobbie Mainoo. As reported by the Manchester Evening News on Thursday, there is a genuine chance Mainoo could be sold by United this summer amid a lack of progress over a new contract. Talks have been ongoing over a new deal for the England international since last March but a breakthrough is yet to have been reached. Mainoo is under contract at Old Trafford until June 2027, with the option of an additional year, meaning United could tie him down until 2028. Both United and head coach Ruben Amorim value Mainoo and it is understood the club firmly believes he has the capacity to reach the very top. The 19-year-old excelled in his first season as a Premier League player last season after overcoming a pre-season injury that ruled him out until November, resulting in him securing a place in the England squad for the European Championship and helping them reach the final. This season, however, his individual form has been impacted by United's collective struggles. He has struggled to impose himself on games, often appearing fatigued after an extended and gruelling 2023/24 campaign. He has not been without his injury issues this season, hampering him find any rhythm, while his long-term position is yet to be determined under Amorim. Despite the fact United need to balance the books and generate as much money as possible via player sales this summer, Mainoo is not a player they will be looking to actively sell, and nor should they be. Instead, United should be aspiring to build Amorim's team around him. Links connecting Mainoo with Chelsea have come and gone, and will likely resurface the closer we get towards the summer transfer window. Chelsea have also previously been sniffing around Alejandro Garnacho. Chelsea are one of very few clubs who appear to have a bottomless pit when it comes to finding the funds to secure high-profile signings. But are they going to stump up a fee possibly in the region of £70million for a player in Mainoo that has not had the best of season's and is still finding his feet? Furthermore, United, amid the way the market has gone in recent years, will probably believe they can command an even higher fee amid his potential. If he stayed at Old Trafford and has a flourishing 2025/26 campaign, United will be within their rights to demand an even higher fee in the summer of 2026 if no breakthrough has been made on securing the midfielder to a new deal. And the plus-one option United have on Mainoo's current deal enables them to tie him down until 2028, offering an extra year to weigh up options and potentially hold out for the highest possible price if Mainoo's form improves on the pitch. With Mainoo capable of improving and United holding a contract card, the club have two security blankets that can prevent them from having to cash-in this summer. However, the elephant in the room is PSR - and that could test their resolve.