According to the RxJS 5 MIGRATION.md it looks like shareReplay() been removed.
shareReplay()
.publishReplay(1).refCount()
Happy news, shareReplay() is back in RxJS 5.4.0: https://github.com/ReactiveX/rxjs/blob/892700dd4f5d5e5f9ae9276ede32208f4390c5e9/CHANGELOG.md#540-2017-05-09