Blinking to the ethereal plane does not halt the fall.

Nothing within the Blink spell or the Ethereal plane's description suggests that you lose momentum during your short existence within the Ethereal plane.
Thus, at the beginning of your next turn, your falling distance in not set to 0. Once you hit the ground, you take the full damage associated with a 510' fall.

A 'lenient' DM may reasonably apply the optional rule for falling from XGE because while you're on the ethereal plane you can basically hover/fly.

If you’d like a flying creature to have a better chance of surviving a fall than a non-flying creature does, use this rule: subtract the creature’s current flying speed from the distance it fell before calculating falling damage. This rule is helpful to a flier that is knocked prone but is still conscious and has a current flying speed that is greater than 0 feet. The rule is designed to simulate the creature flapping its wings furiously or taking similar measures to slow the velocity of its fall.

But that won't help much in this scenario because you would still take the falling damage associated with a 480' fall.

However...

The Ethereal Plane also disobeys the laws of gravity; a creature there can move up and down as easily as walking.

...if you ready your action to move on the Ethereal plane you could reasonably halt your fall.
This is similar to what a flying creature can do according to XGE's optional rules for falling:

If you use the rule for rate of falling in the previous section, a flying creature descends 500 feet on the turn when it falls, just as other creatures do. But if that creature starts any of its later turns still falling and is prone, it can halt the fall on its turn by spending half its flying speed to counter the prone condition (as if it were standing up in midair).

It is fine

Stronger than the original, about the same as a half-elf, which itself is not the best race, so this cannot be overpowered.
This homebrew race is so far from the original in the PHB that I would call it something else entirely, but it is not too strong.

Why is the original weak?

It is not about the number of features a race gets, but how often they come into play and how much they matter¹:

• Resistance is rare and powerful in 5e, but of course it is hard to know at character creation what will come up most
• Breath Weapon is used with a tertiary stat, has horrible damage, and takes up an action
• The abilities are not complementary, only a combination of mental stats (like Int+Cha) would be worse. Beside Paladins, only some niche builds find Str + Cha useful

To make matters worse, Resistance goes against Breath Weapon, in that for the first you should pick something common like fire or poison, for the second something rare like acid. With the current setup, you should prefer Resistance, as Breath Weapon is close to useless for the following reasons:

• For any reasonably optimized character, about 3 enemies have to be in the area just to break even with your usual damage output²
  • Most of the time so many enemies cluster only around one of your fellow adventurers, whom you do not want to hurt
• It costs an action, and very few characters can do something useful with just a bonus action

Yours compared to the original and half-elf

Dragonborn

You replaced the dragonborn's best feature (Resistance) with some new, less useful ones. They come up rarely, and are not really powerful. All things considered, I would say the overall usefulness decreased.

The big change here are the ability modifiers, now dragonborns are good choices for Bards, Sorcerers, Warlocks and Paladins.

Other features

• Size. Same as original
• Speed. Same as original
• Breath Weapon. Same as before (pretty weak, see above)³
• Draconic Swimming Training. Very niche, close to inconsequential
• Horns. Very few weapons are worse, so why would you use this?
• Goring Rush. This is closest to useful from all the features, still significantly worse than Resistance would be. Above level 4, doing 1d6+Str damage is not much better than 0, compared to your usual damage output
• Glider Wings. Similar to swimming. Inconsequential compared to Aarakocra
• Languages. Same as original

Half-elf

Same ability modifiers, different features.
For most classes, I would still prefer the half-elf, two skills and darkvision come up much more frequently than gore attacks.

Simple fix to the original

Breath Weapon should either do decent damage, or should cost less.

If you want tactics to be relevant, increase the damage die to d10 from d6. In this case 2 enemies are usually worth an action⁴.
If you want it to be easy, leave the damage, but make it a bonus action.

Do not change anything else.

1. Variant Humans were still the best race for most builds even without the extra skill, with only one feature (the bonus feat)
2. Dual wielders for example lose their bonus action attack too, if they use their action for breathing
3. Actually a bit better than the original, at least it does not clash with the Resistance now
4. Unless you would have advantage on your attacks. Similarly, Breath Weapon can be useful if you have disadvantage on your attacks