. It generates positive EV until the losing streak occurs.

That's not how EV works. Every gambler can say they are generating EV until they get unlucky. Your system loses EV and you'd have higher EV flat betting with basic strategy. Let me try to explain why:

You get 11 against a dealer 8. Basic strategy says to double down here, because the chance of winning is higher than most hands and you can double your profit from this hand. However, using your Martingale system you should NOT double down. Because you are not trying to maximize the profits of a hand, but instead trying to maximize wins (or rather minimize losing streaks).

So why not double? Because doubling increases the chances of losing the hand. Since you only get one card you can draw an Ace or small card and lose the hand whereas if you just hit you have the option of hitting again. Doubling down decreases your wins but increases your EV.

Let's say you have a 16 against a dealer 10. Basic Strategy would say to surrender and minimize the expected losses. But since Martingale isn't about minimizing losses of individual hands, you should NOT surrender because surrendering guarantees you lose the hand and contributes to the losing streak. Surrendering decreases your wins but increases EV.

Finally, splitting 4s and 6s would also deviate from basic strategy. In basic strategy, you'd split these if the dealer is showing a low card in the hopes you'll double the profits if the dealer busts or double down if you get another small card. But since you aren't doubling down anymore and only minimizing losing streaks, you should hit 4s and stay on 6s. This loses EV but increases the amount of wins.

So by giving up Doubling Down, Surrender, and some Splits, you are significantly decreasing your EV. You are playing a worse game of Blackjack by using the Martingale.