I strongly support the Founders Reward as it is currently specified (10% of the total supply of 21 million ZEC, all distributed before the first block halvening), but I very much oppose any extension, and I would work vigorously to organize an opposition to any proposal to extend it.
To the extent that those associated with ZcashCo (owners, directors, and employees) still hold significant amounts of ZEC at the time that the Founders Reward runs dry, they will still have a strong incentive to continue to contribute to Zcash because their contributions could increase the value of their ZEC holdings.