No one said the ‘Series 5’ Apple Watch isn’t coming, if you read back, there isn’t really much indication through leaks (both hardware/software) that a Series 5 may be probable for a fall release.
There is no indication either way. But the September event is basically right around the corner, so just wait for that. If there is no S5 in September, you‘d have to wait until 2020. Or get the S4, which is still amazing.
Someone brought up that it is strange there are ZERO rumors for 2019 regarding the Apple Watch besides a ceramic case. I think maybe they will do a small spec bump to the series 4 a la Airpods 2? Or maybe release a new SS color? It's odd because even when Apple had released The Rose Gold and Gold Sport in 2015 those were rumored prior