If the club makes an appropriate offer, Mourinho and Abramovich won't stand in Cech's way. Petr has been extremely professional throughout his career, a relative modern-day legend for Chelsea - both on and off the pitch, so he has earned his share of goodwill, and they'd rather he leaves on amicable terms. Also, Jose and Van Gaal have an excellent professional and personal relationship, and that might even tilt the balance United's way vs Arsenal. However, if Wenger make an equivalent bid - agreeing terms with Cech might pose more of a challenge from a personal standpoint. He has been living in London for over a decade now, and his family is presumably comfortably settled in the city. Generally, footballers of a certain age take all of that into consideration; would he then rather favor a move crosstown to Arsenal ?
Anyway, that aside, from a strictly on the field perspective, Cech would be a quality replacement for De Gea. Not as comfortable with the ball at his feet but gets the job done with relative ease, immensely experienced both in European and domestic competition, still one of the best in the league, and not as big of a risk as some of the younger candidates who aren't used to English football, necessitating another steep learning curve like David's. Cech would pretty much hit the ground running and could be the #1 for 5-6 seasons, if not more.
