LOL can last 10+ years. Starcraft 1 was pretty relevant for 9+ years. LOL is already 5 seasons in, about to enter 6th year. The game itself has plenty of life left considering it has the biggest player base that is still growing.
What normally kills competitive games tends to be balance and barrier of entry. Riot is doing great in terms of balance considering the fact that the game works on meta shifts which means it doesn't get stale. If you look at games like Starcraft 2, it doesn't have a long shelf life; strategies tend to be rock-paper-scissors and it's hard to undo foundations of the game without expansions. This is why last year SC2 tournament was nearly all over in last than 30 min game time. Why? Player surrender by 3 minutes because Z always loses to Y no matter what the player does at that level. LOL has the benefit of meta-shifts, reworks, new heroes, and constantly new balance that tunes item or maps
With that said, the barrier of entry is starting to be a problem. Certain companies have multiple teams, a huge amount of employee; managers, pick/ban experts, personal analyst, game houses...etc. While it might not seem like a problem, these companies or organizations have multiple teams, remember Samsung Blue and white? Dominated! Riot realized that quickly and they stopped it. What do these organization do now? create parent companies, go to another regions, ie Dignitas in US and one in EU. It might not seem like a problem, but that's what makes regular players hard to enter the the LCS.
Barrier of entry is also in the Challenger Teams. They tend to have low budgets and they are easily DOSed by other teams.
AS far as compensations go, this isn't a problem. It's a problem when these teams start using these funds to hire more employees. While it might sound good, it just means that it's harder for teams who aren't in the LCS to get in because they don't have all those benefits. Now if you think these benefits like coaches, managers..etc don't help, why do these teams bother getting them? Obviously, on some level, it helps.
Also, as far as DL or other pro player who starts telling players not to pursue pro careers, I agree. Quite honestly, NO game can lost forever. It's not sustainable and it's unpredictable. Your best bet in life is to go to school, finish college, and maybe take a few years off to play LOL. Oddone on his stream said it the best way. Eventually you either get out-beat by new fresh talent, or you start to outgrow it (i'm summarizing).
Even if Riot compensates teams with another 50-100k per split, it wont help much. Considering they will hire more employees, and inflate expenses, it really wont completely go to the players. The best way for these organizations to raise money is through streaming, ads, and product placement ;D.
With that said, pro players are welcomed to leave if they think other games have better pro career options. I'm sure there are plenty of game companies that pay you to just play in their tournaments. I'm sure there are other games that are always top 1 in twitch viewership, and I'm quite sure, there are plenty of games out there that USA recognizes as E-Sport. Hell, im sure plenty of colleges have teams for other games, which offer scholarships.
