No way, not until rockets take humans to any corner of the globe within 40 mins will a global league ever come to fruition.

Maybe with how technology goes, Musk might have built supersonic rocket planes, but teams would still be on a massive road trip. And it's taken how long for Seattle and Las Vegas to finally look like getting teams. Then there's the cost of franchises, couple of billion a team makes it totally unfeasible.
Maybe an end of season tournament, fiba rules would slow down NBA teams to start with.

Yes.

Look at how multi-sport clubs such as Bayern Munich and AS Monaco, with the means to do so from football, have all of a sudden resurrected their basketball sections from the amateur doldrums to full professional level and ascended to their respective national first divisions and EuroLeague in next to no time.

They are getting their ducks in a row.

The majority of visitors to nba.com are from outside the USA, theres probably other metrics with similar stats and the NBA knows this. They'll follow the money.

NBA are salivating at name brands like Barcelona and Real Madrid.

That won't happen but if they want the advantage of something like that, why not buy the Euroleague, brand it with NBA joint venture marketing, pump them with money and then have a Champions League style tournament?

Have the Euro/champs league finish by March/April to give NBA teams time to steal the players for the last few months of the season to top up their rosters like Bogut did with Kings/Warriors.

NBA teams take the piss when it’s not the playoffs, the Euros would take it seriously, the best borderline nba players would enjoy a bit of euro, champions league then finish in the nba for playoffs.

It wouldn’t necessarily be NBA teams smacking Euros on a global scale, it could be competitive-ish.

Yes, EuroLeague will somehow integrate with the NBA and that's why clubs are scrambling to be part of it since that will be the gateway.

They've already taken the first step towards American-style franchising by guaranteeing many of the spots to power clubs in case they do not qualify via their domestic league.

Google says flight time NY to Los Angeles is 6hrs. Fly NY to London/Madrid adds one hour. It could be done.
When expansion into Europe is mentioned, there are 2 alternative approaches mentioned.
The first approach - which I think will happen - is a piecemeal expansion adding one or 2 European clubs to the US eastern conference. Here London is invariably nominated. The attraction of this is that there is plenty of interest in the UK in the NBA; there are strong commercial linkages which makes it easier to tap sponsors.
The second approach is more dramatic - involving the integration of elite clubs in the Euroleague as a separate conference as curtley mentioned. This is more problematic - more administrative hassle associated with upending the structure of both the NBA and Euroleague competitions. Keep in mind there are substantial legacy $ invested in the Euroleague from private owners that will be put at risk. Smaller clubs in Europe - notably in eastern Europe as well as Portugal - will be concerned that their clubs will be playing in a second rate comp.

Will Vegas actually get an NBA franchise? It's the Gold Coast of American sport (how many successful, long staying nation nail teams hav they had?)

It’s ok to think of travel from New York to Europe, but what about Miami (or any Californian team even worse) to Europe?

I think the only things the NBA would be interested in would be pre or post season games, such as a trans-Atlantic knockout cup. And getting into bed with the big soccer/basketball clubs. FIBA and Euro basketball admins might be fine with this, but what about FIFA and the Euro soccer admins? It could be a matte4 of watching sharks tryn* to devour each other.

Will Vegas actually get an NBA franchise? It's the Gold Coast of American sport (how many successful, long staying nation nail teams hav they had?)

Las Vegas was only recently awarded their first and now second Big 4 franchise. Both have been a roaring success.

And getting into bed with the big soccer/basketball clubs. FIBA and Euro basketball admins might be fine with this, but what about FIFA and the Euro soccer admins? It could be a matte4 of watching sharks tryn* to devour each other.

Multi-sport clubs have been competing in both sports for a century and will continue to do so. FIFA have no say in it as they only implement the laws of the game in addition to organising international (i.e. not national nor continental) tournaments.

In Europe clubs enter their junior, youth and senior aged teams in various league and cup competitions in their own capacity, they aren't enfranchised to one entity like the American system. In the case of multi-sport clubs this can be replicated over several disciplines.

Err enfranchised should read as franchised.