Resident Evil 4 is considered one of the best games ever made, and certainly one of the most influential. It single-handedly pulled the Resi series from a rut it was stuck in, and rebooted it for a whole new generation by jumping to a new location, swapping out the combat mechanics and switching from zombies to... slightly faster zombies. While some fans lament the overall era these changes ushered in, there's no denying that, for this one entry anyway, they totally worked.
Of course, because nothing is sacred, it looks as though Capcom is planning on remaking Resident Evil 4 in the near future. While that's not totally unexpected, considering the recent success the company has seen with remakes of 2 and 3, the key difference is those games were remade in the mould of Resi 4's mechanical foundations, offering a radical change this remake won't benefit from.
However, if the release has to happen and the publisher wants to tinker with the sequel and update it for modern audiences, it doesn't have to totally be a bad idea. Nothing is perfect, and as hard as it might be to admit, neither is Resident Evil 4, and there are a few areas Capcom can improve upon with the update.