I think should be able to maintain.
look at standardcharted. their 1.88% bonus saver already there for so long already.
This should last at the minimum 2 years.
However Bonussaver returns are much lower:
For 50K balance in Bonussaver (on annual basis):
Base interest @0.10% on balances above 25K = $25
Bonus interest @1.88% on first 25K = 470
Credit card spend of Min 500 spend rewards: 0
Total payout for 50K = $495 or 0.99%
For 50K balance in OCBC 360 (on annual basis):
Base Interest @ 0.05% = $25
Bonus interest @3% = $1500
Max CC rebate (Frank card online txn 500 pm @ 6%) = $360
Total payout: $1885 or 3.77% pa
Also, in case you don't want to spend anything on CC, SCB Bonussaver will earn you just 0.10 % while OCBC 360 can still earn 2.05%!