It is curious that whenever I voice doubts regarding SPaceX I get quite some downvotes. But I digress.

The main reasons I am not that optimistic anymore regarding SpaceX are financial, mostly based on some doubts I developed regardintheir real launch prices ( I know that there is no "standard" launch) and the fact that encumbents are waking up.

So, as far as financials are concerned 100 launches representing $12B mean an average of $120M per launch, a far cry from the $62M they are advertising. These price are not that far of from, say, Ariane. Sure, it's an average, which is exactly my point. Underbidding other commercial providers is easoer when you get highly priced government work to susidize these commercial launches (ULA is a nice case in point regarding the revenue and profits government work is providing. this also explains a lot about ULA, but that is a different topic). SO the first issue I have is the hype regarding SpaceX costs which is purely based on advertised numbers. The discrepancy was also there up to 2015 (wsj published internal docs and real number up to 2015 in Junuary 2017). So, to me it seems that SpaceX is doing what everybody else is doing in that sector: taking government contracts to cross finance commercial business. Be it development contracts (SpaceX and Boeing for manned space flights), purely military programms (F-35, Eurofighter,...) or direct state subsidies (Airbus, Boeing tends to get the government money through military programms). I'm not judging here, it is simply a common industry practrice. I totaly agree that SpaceX has a much lower development cost structure as purely private company without any political and bureaucratic beef, I just doubt that this advantage is as great as I believed it to be.

The other threat I see is now that incumbents woke up competition for comparative launchers is getting tougher. While Ariane-5, as one example, was intended for a shuttle-like program Ariane-6 will be much closer to a Falcon-9 and will allow lower costs per kg-payload. Last estimates put in almost in a ballpark region of Falcon-9s based in advertised prices not taken the above emntioned averages into account. As a result it is reasonable to assume that SpaceX cost advantage will not stay for ever. The other oart, somehow related, is reliability. Both, ULA and Ariane, have a better launch record than SpaceX. That reused Falcon-9s are now advertized as "launch-proven" instead of reused (nice counter-point to a expendable launcher when you look at a unit level) kind of confirms this and is again pure marketing. Not sure how much marketing factors in when someone wants to launch a $100M plus payload so. And the final factor is that incumbents have really deep pockets, SpaceX needs venture capital.

All of this doesn't mean that SpaceX did not achieve incredible things, they showed how fast and cheap development can be without political BS. They developed a reusable rocket (finacial aspects non-withstanding). They breathed life again into the American space programs. So when I say less optimistic that implies a very high (hyped?) starting point.

EDIT: Ariane-6 is scheduled to replace the Ariane-5, with an unclear development up ahead it it seems obvious that demand is shifting to a provider with an already developed launcher. As you see I did not look to deep into ULA yet, so everything is coming down to Arianespace - SpaceX comparison.