Marc Surer, a prominent German-speaking commentator, said alternate marques like Michelin and Bridgestone could enter F1 "at short notice" to replace a departing Pirelli "if they wanted to".
All Formula One teams except for Mercedes tested a new range of Pirelli tyres at the Silverstone circuit during the three-day Young Drivers Test.
Red Bull team boss Christian Horner said the reigning world champions could be next in line for testing with Pirelli.
Pirelli is replacing the 'hard' with the 'soft'.
Pirelli heads to another legendary venue in motorsport: at the Nurburgring in Germany.
Reports concern Pirelli again! This time they are accused of not filing a report to the FIA that they had changed the construction of the tyres prior to the British Grand Prix.
Horner is convinced that the 1000 kilometres of testing that Hamilton and Rosberg did in Barcelona had a direct effect on Mercedes' rapid development in the last few races.
Tom Cary is reporting not only Ecclestone's 2014 deal with Pirelli, but also almost all teams