For Apple, the opening of the ecosystem proceeds apace in Europe.With it, however, comes the potential to realize some additional revenue streams.And what happens in Europe, with Apple at the epicenter, may be a harbinger for Big Tech in general, operating on the continent.Last week, Apple made a move to offer competitors access to its tap-to-pay mobile wallet system. The overture seems geared toward ending an antitrust case in the European Union.Now, Apple is gearing up for sideloading, a term and practice ...