This is something I have researched over many years and there were often opportunities for good investments simply by judging where the winners would be from a customer perspective.
Well managed best in class businesses have generally excelled and the long term success stories such as Neteller, Betfair and well run outfits like 32Red have resulted in good investments whereas the strugglers such a Ladbrokes,BWIN Party and more recently William Hill have fallen out of favour with both customers and investors alike.
My own feeling is that the industry consolidations will continue albeit at a lesser pace without "low hanging fruit" opportunities for investors.
The only exception may be Gaming Realms (the owners of the dreadful Slingo) who appear undervalued and the very much underestimated Evolution Gaming who may go on to dominate for quite a while after acquiring both Netent and BTG. Well managed and with a proven track record they may well become a world leader rather than a European leader.
Playtech will probably be bought by Draftkings at a slight premium however for me Playtech are simply not cutting edge enough to compete now and thet will lose market share and influence as hungrier and more innovative software houses shape the customer offerings in future.
I would expect a few fringe opportunities to arise out of compliance monitoring and software and these may be where any really juicy returns are ri be made for investors in the gambling sector now.